How do I get around that awkward your all in a tavern feeling. And how can I get around the players not sure how to act out there characters early on. I'm starting a new campaign and dont want to do the your all in a tavern thing it works but feels... underwhelming  I guess. 

i'd suggest starting them in the middle of something like they start at the beginning of a dungeon with no idea how they got there or some dude is trying to find someone to do a beginning quest for him and having try outs, that or a session 0 for getting smaller groups to the starting town where they'll meet with the other 1-2 person groups

You are not going to be able to get around players not being sure how to act out their characters early. That comes with the territory.

My group is about 15 sessions in, and even the very experienced roleplayers have said that they are still "feeling out who their character is." This not only can happen... to a degree it should happen. Characters are not static icons who never change or grow. They start out as new adventurers, like Luke Skywalker meeting Ben Kenobi on the desert of Tatooine. (I find it hilarious that chrome's spell check recognizes "Tatooine" but not "roleplayer" as words... ahem.) Luke didn't know who he was himself in that first movie, and he grew into a hero over time... one with depth, one with motivations -- motivations that were different from the farm-boy "I want an adventure!" ones in the first movie. By the end he was trying to turn an evil villain no one thought could be redeemed from the Dark Side, threw away his lightsaber, and said "I am a Jedi, like my father before me." And he saved his father, not be being an adventurer, but by being merciful. Would you have guessed that from his intro scene on Tatooine? Nope. But that's what happened over 3 movies (3 "adventures" in a long campaign).

So I would say don't worry if your players are still feeling out their characters and things are awkward at first. That's how it's supposed to be. They will develop their characters over time, as the campaign goes on. 

That's why I like long campaigns. You can't really do that development over 3 sessions -- it takes many sessions and many adventures to develop a character from start to finish.

One thing that works for me is to start the characters right at the beginning of a dungeon, saying they’ve known each other a few days now, and giving them a recap of how they got there (a bit like the start of Phandelver, in medias res). Only thing is this could result in a little less role play. I’d encourage you not to shy away from the “meet in a tavern” idea though...it’s classic because it works so well.

"You start at the entrance to the dungeon, having gotten here by X means," is a classic old school way to start a dungeon crawl. Works great.

My DM actually read through everyone's draft background and ask why their character decided to adventure. He then links the character's back story to the campaign after talking to each player.

My campaign is railed but it rails to the character's back story. The 1st main quest is actually a couple of character's quest through their backstory. Few characters have the Soldier background so the "local government" (DM) orders (asks) them to help the quest. The rest of the group are mercenary or adventurer who is looking for some money. So when the reward said "20gp upfront and 100gp after the quest completion", it is hard to refuse both IC and OCC. 

Please note all the backgrounds and backstory are players' free choice. My DM just intergrade them into his world. 

in the game I'm currently running I worked with my player individually with backstory and came up with a reason that they would be in a designated town and yes Tavern but thats not where we started. After recapping this information we skip forward two days as they are traveling in group to another city in search of work.

It's always the one part of a story i hate writing because things can and do feel so cliche. Sometimes cliche and cheesy can be fun. I also Run a Star Wars game and had no problem starting my players in a basement killing Wamprats.

I'll second what a lot of others have said - It is really hard for most people to be able to jump straight into roleplaying, so don't be worried if the players take a couple of sessions to get used to playing their characters. 

As for starting the game, I find that starting in medias res can be a great helper - not just in getting things moving in an entertaining way, but also in helping players to get used to roleplaying.  Considering in the abstract how their character feels about the world and everything in it is really, really challenging (even for experienced players), but throwing the players into a dilemma or action scene immediately focuses the mind; Are they excited to go on an adventure, or nervous to be leaving home for the first time; Are they fearless in the front line of combat, or more cautious and keen to hang back; Are they curious to talk to a captured bandit and understand them, or do they see them as criminal to be executed. 

The opening of Lost Mine of Phandelver is a really good example of this - as the DM you can set up that the reason these characters have been thrown together is because they have all taken a job as caravan guards, there is the opportunity for an NPC caravan driver if you need to help direct or encourage the players (handy if these are first time players and might not be sure of what they can do), and the discovery of the horses/saddlebags and following goblin ambush give the players a focus for their roleplay, all with the added bonus of immediately hooking them into the main story thread of the module. 

If you are running a homebrew campaign you can still do the same thing - the key points are to make sure that your opening action scene provides a reason for everyone to be in the same place at the same time, and to give players a situation to react to.  Bonus points if the scene is able to highlight different elements of your PCs personalities, and/or ties in to the main plot in some way. 

Edit: grammar :(

Start before session 1...if only there was a name for that....tip of my tongue.

Have a session that isn’t about playing a dungeon or getting quests or social encounters but is just people discussing their characters, who they are, how they fit with the world, how they fit with eachother. Make it casual, give them a chance to talk about what motivates them, work out the things they don’t want to tell eachother. Chances are a natural starting point will emerge.

Failing that I like a good last will and testament - they are all strangers that have come into contact with the same person at some point in their life and are called together for a reading of their will ....then shenanigans

My personal favorite is some kind of Call To Adventure.

While in X you 'overhear/see a notice/are begged to...' about a deadly problem that the mayor/governor/king/captain of the guard can not solve by themself.  They are asking for anyone that thinks they can handle it to come to Y location for more information.

Once you arrive at the mayor house/town hall/ etc.  you and several others (aka your new best friends for life/party) are told about the horrible Z and asked to attack it together because clearly Z is too powerful for anyone to handle on their own.