I am looking for tips on my roleplaying skills, things like voice and quick thinking for replies in conversation. I have been thinking of making a noble character.

Sometimes it’s difficult to answer the simple question of, “What would my character do in this situation” because you’re used to making decisions based on your own life experiences, not the characters.

My advice is to spend some time figuring out the characters motivations based on the backstory/background you have envisioned for the character. As a noble, for example, are you interested in obtaining power? Are you set in doing what’s best for the people you may rule? Are you the 3rd son of minor nobility and perhaps neglected by your parents who have focused on sons number 1 and 2, prompting you to lead a life of adventure? Do you come from wealth, and are potentially oblivious to the downtrodden because you can’t empathize with their struggle? Or conversely you feel guilty about never struggling and make charity a priority? Do you dress in finery? Is there a dark family secret you’re running from, or embracing? Does friendship matter to you? Or loyalty?

”Quick decisions” tend to come from having a greater understanding of who you are and what you want. 

Did you become a a paladin because honor and justice are important to you? Or perhaps a fighter because despite your upbringing you haven’t the knack for political intrigue? Maybe a wizard because hey magic is cool and my family has access to a wonderful library piled high with books on arcana. 

Anything and everything...that’s the beauty of D&D. 

Some minor tips that can also assist is writing down some ideas of things you think the character might say in casual conversation.  Son of a noble merchant that deals in shipping might talk about how the weather lately is bad for shipping.  Or an awkward one might talk about exchange rates with Chult.  

"I am looking for tips on my roleplaying skills, things like voice and quick thinking for replies in conversation."

Relax.
Don't worry about looking foolish.
Stop overthinking.

Learn from the best: Children aged 3-9 years.  Roleplaying "skills" are nothing more than the ability to pretend you are somebody else. You know, the sort of things adults try to stop you doing.

Talk to yourself more. Especially on the bus. :)

As for quick thinking replies - just say the first thing that comes into your head. Your sub-conscious is probably better at this than you are, and unlike real life, there are no real consequences. 

Edit: Leave your phone at home.

Each of the characters I have played come with a very distinct personality; the brooding, power hungry drow sorcerer, the pretentious and effeminate high elf wizard, the arrogant and abrasive human ranger/rogue, and the charismatic and theatrical dwarven barbarian. 

When you read those brief descriptions you had an image pop into your head almost immediately. The words were evocative and may have made you think of a movie character or some character in a video game. Just as with those movies and video games, I create my character starting with words that describe the character. Pick 2-3 words that describe their attitude: humble, nervous, arrogant, prideful, bashful, narcissistic, lazy, etc. and write them down. Then pick a few words that describe their appearance; muscular, disheveled, haughty, well kept, limping, scared face, etc. and write them down. Then pick some words to describe their motivation: wealth, glory, fame, retribution, curiosity, wanderlust, obligation, work, etc. and again write them down. This is the character I use in a game I'm lucky enough to sit in on sometimes:

Utgar Baulderkin, Dwarven Barbarian (Entertainer: Gladiator)
Charismatic, loud, entertaining
Lightly scarred, taller than average, super muscular build like a body builder
Entertainment, reclaiming pride from a scandal, duty to friends/family

That gives a good mental image of what and who the character is, from there just play to the words. When combat starts Utgar starts smashing his war picks together shouting "It's time to play! The Iron Ursine is here!" as he goes into a rage and pulls down his bear mask. 

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As to the voice acting bit, don't concern yourself so much with it. Play with how you speak and where you speak from, it sounds weird at first, but it's fun. Try pushing your voice through your nose, try talking from the bottom of your chest, talk from the back of the throat. Let more air out while you talk, think whispering, stick your jaw out while you talk, put your tongue against your top teeth as you speak. Each of these little things will change how you sound, and the more you play with it, the easier it will be to find new voices.

Utgar has a gravelly (back of the throat), deep (from the chest), voice.

Accents, however, are difficult if you are looking to nail a particular one, instead; just play with how the words sound. Make the 'a' sound in 'way' different and turn it into 'why', make the word 'what' sound like 'wot', we could change 'are' to 'or' and the 'th' sound into a 'd' sound. With little changes like that we can change the entire voice and sound to something completely new. It may not be a perfect accent, but it does give the idea that your character comes from a different place:

Normal: "It's time to play! The Iron Ursine is here!"

Utgar: "Iss tam ta ply! Da Ah-urn Ur-soin iss ere!"

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You'll sound and feel silly for a while, but as you settle in it'll become natural. I have my players in tears watching me switch from the fast talking, nasally voiced Warren to the soft and almost impatient voiced Aerik talking to myself. They hear the horrible Spanish accent of Gazmon (think Indigo Montoya from Princess Bride) and I watch the table prickle as they all want to kill this guy. King Uriah is immediately known because I'll close my right eye and talk without moving the right side of my mouth. The Gnome siblings Tik and Tak with their hyper fast, overly large words, will cause my players to run from these walking accidents. Ximina with her soft and wispy, cringe worthy, Ukranian/Russian type accent reminds them that they're at the Boar's Head. I, having had to come up with so many NPCs in two years, have officially become schizophrenic....

One tip I've found is to assign a real life actor to an NPC and then use their description/accent/mannerisms as the NPC. Don't tell your players what actor it is but it can help by making a 'shortcut' of traits and characteristics.

The key for quick thinking and replies in conversation is to have a clear description of who your character is and how they will respond to certain situations. Otherwise, people will often fall back on what they know, which is often their own personality or previous characters they've played.

If you're working on doing a particular voice, practice it a few times outside of the session. Record yourself if that helps. Practice is really the only way to get a particular voice to "stick." And definitely look for examples of the kind of character you're trying to achieve.

As a former actor I find that nothing replaces rehearsal. As another post said, talk to yourself on the bus or wherever). Think about how your character would react to different situations. Did he just meet an old friend? Maybe think of a signature 'tag line' that only YOU will say like 'My brother from far away is here!' Even the smallest situations, which might not come up very often, will do. How about a good trade with a merchant? Or a bad trade? Negotiations with a rival noble house? Is your character fair and kind to the lower classes or are they a snob?

Another good technique is movies. Some of the best lines ever in a game were said as a throw-away in a movie and nobody remembers them. Every time one of my underlings expresses fear at the task ahead I ask him to 'find a piece of stout timber about 2 feet long, then lass it to their spine. It needs stiffening!'

The tips on voices above are good too. Don't try to reinvent a whole language, focus on a couple of consonants and vowel sounds and use them consistently. Listen to how others talk (again, movies are good here).

Above all, have fun with it. When it becomes too much like work, the fun stops.

Here's a site I give my players with great tips: http://lookrobot.co.uk/2013/06/20/11-ways-to-be-a-better-roleplayer/

Another that goes over some ideas on creating some flaws: https://www.helpingwritersbecomeauthors.com/character-arcs-2/amp/

For me, when I create a character, I like to KISS (keep it simple, stupid) and set up a few lynchpin elements to define the character, simple concepts and firm decisions that allow me to build a framework around, like the poles of a tent that define its shape.  For example, my Dragonborn paladin is social, patient, prefers to talk over fight, and likes to drink...a lot.  I take these pieces and think "Hmm, ok, so social and patient, not in a hurry, so likely talks slower than most, doesn't stumble over his words.  Maybe a Southern accent?"  I go through some ideas and concepts, situations that he might have had to face, and decide how he would have dealt with them to provide more structure to his personality.

The idea, IMHO, more important than accents and other superficial things, is to be able to fully immerse yourself into the character such that you answer/respond without having to think about it first.

"LEAVE YOUR CELL PHONE AT HOME"      

So THIS. Leave it in the car, turn it off and put it in your bag, take out the battery, and stick it in the freezer. No cell phones has been a house rule for many years now.

Maybe you aren't aware of how annoying that player is who worships their cell phone. DON'T be THAT player.

Thank you, Plundered Tombs.

Quote from Payshunts >>

 

"LEAVE YOUR CELL PHONE AT HOME"      

So THIS. Leave it in the car, turn it off and put it in your bag, take out the battery, and stick it in the freezer. No cell phones has been a house rule for many years now.

Maybe you aren't aware of how annoying that player is who worships their cell phone. DON'T be THAT player.

Thank you, Plundered Tombs.

 I used to be that way, then DNDBeyond, OrcPub, etc made online character sheets much more efficient.

Some really great tips! 

I've found it really helps to find something exciting about 'getting into character' - and put a bit of effort into getting into your characters head. For example, I once DM'd for a group in which the wizard didn't just record their spells on a standard sheet. She had an ornate journal that she used for a spellbook, and in battle would dramatically flick to the correct page, carefully describe the components, and really bring the spells to life as she cast them. She'd use that prop out of combat too, and her character provided some of the best, most immersive roleplaying at the table.

She later explained she finds roleplaying hard, but physically writing in a spellbook helped her bring about the excitement her elven wizard had at scribing, and having all of that arcane knowledge to hand. Kind of cool, really.

Generally I think three things go through my head when making quick decisions, in this order.

1. "What do I think I should do?"    What's your solution as a person regarding the situation.

2.  "How would my character go about it/Who am I?"    Not what your character would do specifically, but how do make your decision be have characters influence.  More often than not they will be the same, just with a little spin on it like an accent or some added stubbornness.

3. "I do it."   My pet peeve is people asking if they can do something. Yes you can.  Just do it, and things will work out, and if they don't that's part of the fun.  At worst, your input doesn't have any impact, but it's way better than thinking yourself to death by saying nothing.

However, you also need to think about what others are thinking, and make things work out.  Sometimes you'll want work with others, and other times you'll want others to work with you;  If you feel like you're hogging the spotlight, or someone is just shy, try encouraging your table mates into an interaction.

1.     "Should I do anything?"  Usually, most interactions are best done as a party, but sometimes you need to think if you have any/no reason to intervene.  Would your input hurt or enhance their interaction?  Also, there's no problem with asking or making some sign of wanting to join.  Sometimes just saying "Uh, hey" works.  

2. "Where are we?" What exactly is the situation, both physically and in the characters head?  Are you having a drink or are they stuck in a bear trap?  Is it possible that you might not act like your character normally would? Does either character have a different point of view on the situation, or lack key information?   For example, Someone is in a room with something odd going on, and someone else just walked in unannounced?  Are you in the room(in the act), at the door (drawing conclusions), or out the window (either a spectator or even manipulator)? 

3.  "How do we interact?"   Are you trusted friends or are you a leader to his men?    Also does the setting have any implication on your behavior?  You might be sitting right next to them, but your character wasn't.  If you were at the door, based on your conclusion, would you let their behavior slide, or chastise them?  If you were in the room, are you ashamed, proud, or lie through your teeth.  If you were at the window, would you intervene?(see step one)

4.  "I do it"  Once again, yes, you can do it.  It's better to interact with others than let one person do everything by themselves, letting the others sit there.  Just do it.

Boy I put way more into this than I thought I would.This is more something I think about to get into a comfort zone, don't overthink every step you take; if your getting into role playing, though, it's much better to at least feel like you know what your doing than being too worried to interact at all.  Eventually, you won't even remember these and you'll just get into the natural flow of it, just remember that you have to do it first.

Here's an interesting article that sort of addresses some of those pieces, Pin: http://lookrobot.co.uk/2013/06/23/stanislavski-vs-brecht-in-tabletop-roleplaying/

The idea is "party as character".  If you're all "method" and your character is a pure individual with their own motivations, that can create situations where your character is doing their own things, against the party, because "that's what they would do".  IMHO, the goal of a good party role player is finding a way to justify having their character advance the story vs trying to force the story to be about them.

The party or DM wants the party to do something.  The character can be "I would never do that", but that blocks the story, so instead try "why would my character do that" and find a way to advance the story while still keeping your character.

When doing voices, there literally is no such thing as a bad voice. So what if it sounds a little bit Irish and a little bit Indian.  What makes it bad?  Who is to say it's not the right accent?  We're talking about a make believe world. As soon as you speak it, it becomes canon for that world. 

What also helps is to write some slice-of-life-stories about your character. My Half Orc Barbarian has a word document full of daily stuff he used to do in his childhood, like growing up on a human farm by adoptive parents, working with sheep, getting bullied for his green skin and tusks by the other locals. Or a page of story how the farm was in a blizzard so he and his adoptive parents didn't leave the house. His Mom showing him how to knit.
It's become canon because of this that my 7ft half orc barbarian, rippling with muscles and raging on the battlefield, knits scarves at the campfire for all of his party members. Just sitting at the table using my fingers to mime knitting gives the character more roleplay depth. 
As for the voice, I'm still working on that, since I'm female and trying hard to lower it to a more guttural speech.
Try and be comfortable with your group, the roleplay will get easier over time.