So up until now I've only played 2E because that's what my father plays, and I love it, but a friend of mine is going to be running a 5E game that I'll be playing and I'm wondering if anyone has any tips ?

Actually, 5e plays a lot like 2e did, but with a few modern gaming design conventions thrown in, so you won't be in for as bit of a culture shock as say, switching to 3rd or 4th Editions would have been.

Check the articles in the front page or search the forums for similar threads. There's a lot of info, though you'll be fine either way.

Hi Cob4lt! o/

D&D 5ed is a very much streamlined experience, and even little familiarity with RPGs makes it a very simple experience in regards to character creation and managing.
The system as well has seen a lot of trimming-down on bulky mechanics and math skills needed. All checks are still done with d20+[something], but that something is now usually characteristic modifier and proficiency bonus (a numeric bonus that increases the same way for all classes based on level) plus any possible ulterior bonus coming from magic items, which never give more than a +3 anyway.

Skills have been sensibly reduced as well, leaving only a handful of them but there is no point or percentage system involved, it is now as simple as: you have proficiency in a skill or tool due to your class or background? you add your proficiency bonus to d20+characteristic mod, otherwise is just d20+characteristic mod.

For DMs as well the system is more slick, having gotten rid of +s and -s in favor of an "Advantage" or "Disadvantage" mechanic.
Advantage is granted whenever there are situational factors that play in favor of the character/creature performing the task (being an attack roll, a saving throw or a skill check), and allows it to roll 2d20 and use the higher result.
Disadvantage is the other way around: unfavorable situations that make the character/creature roll 2d20 and use the lower result.

Other than this... it's been a long time since last I played 2ed, so I am 100% sure of all the differences, but the above is a very quick overview on how the system works in 5ed.

If you have any more specific questions, me and others will be more than happy to clarify any doubts you might have :)

Thank you ! that's all very helpful

5e takes a lot of stuff from 2e, and is designed to be easy to learn, so I wouldn't worry too much. The one tough part would be making a character, and the PHB contains some great information on how to do that.

It's easy. Plus it's D&D. That says plenty right there.

5e took a lot of the best ideas of the various editions and put them together.  I learned on 2e myself, and honestly preferred it to 3e, which I really didn't play too much.  I played some 4e also, and while I enjoyed it, there were some serious shortcomings that I didn't even realize until I came to 5e.  To me, 5e is the most well rounded set of rules they have had.  it just works.  5e is a little bit less lethal, which I think is good.  My character dying was certainly not my favorite part of old editions. 

Magic works better, unlike 2e, I can make a first level wizard and feel I can contribute.  Back in the day it was like, ok, I just used my Magic missile, I am out of slots, so I can hit something with my dagger and risk my 3 hps, or I can hide behind the fighter until we sleep.  Clerics are fun.  back in 2e my memory is someone being /stuck/ playing the cleric which was just a ****** fighter who had by the goddess better be saving his magic to heal.  In 5e, clerics are quite possibly my favorite class and nobody gets upset if I spend spell slots on offense from time to time.

The "math" is flatter, and easier.  instead of having wacky THAC0 bars on my character so I can figure out what I hit, it's a simple matter of adding my mods to my dice rolls, and if that total is greater than or equal to the AC, I hit.  No more, well I have +3 to hit, and am level 5, so when I roll a 17 with my THAC0 of 15, I hit AC -5.  I'm not positive that my math is right on that hit, and that's the whole point.  You don't have to think about that.  Now, you roll a 17, you add your plus three and you hit everything up to an AC of 20.  Magic items are not "expected" to be part of the equation.  In one of the campaigns I am playing in right now, I'm level 9 and just got rid of my starter gear short-swords.  While magic would have been nice, I never felt like omg, I can't do anything with these crap mundane weapons.  My ability to roll 3's and 4's factored into misses much more than my non-magical weapons did.  it's nice because you can have character concepts with your ancestral sword handed down for generations, and you can *gasp* keep using it.  it's not like you're broken because you don't have a +5 defender.

There's much less choice though in 5e.  2e had a plethora of books you could grab spells and options from.  5e not so much.  There are a lot of cool spells that just dont exist in 5e (why no glassteel wotc?  why?)  All in all, I think you will find that it's a pretty smooth transition from 2e to 5e.  it might be worth getting your dad to check it out too.

That's nice to hear, and yeah THAC0 is certainly weird, when I told the DM for the upcoming 5E game (She's never played anything else) she was quite confused

After playing 5e I think it would be difficult to go back to 2e.  5e just feels smarter.  Another example is saves.  They make sense now.  I played 2e from probably 1988 to 1998 was likely my last 2e game.  If memory serves, the general rule of thumb was when in doubt, save vs death magic.  Now, you save vs the ability that makes sense.  Getting charmed?  Charisma.  Slip on some ice?  Dex.  Speaking of ability scores, they all do useful things now.  Even Charisma, which I remember as being mostly useless unless you wanted to play a paladin, then you had to waste a glorious 17 roll to do so.  Now, bards, sorcerers warlocks...all use char.  It's not "just" a dump stat to put the garbage roll (because there's almost always at least one)

And paladins...you had to be Lawful good.  Why the heck would I be lawful if I am the champion of a chaotic god?  Now, if I want to be a paladin, I can without "wasting" rolls, or being stuck with an alignment that may not make sense.  Now, I'm still going to want that big charisma because it does things for me.  It's not a choice of hmmm, I can make a paladin, and have to drop a 13 or 14 on my str...or I can make a rockin' fighter with a 17 str and put that 14 into con for better hit points and have stats that can help me.

in my eyes, 5e is spiritually 2e, but with common sense.

I played 1st and 2nd edition, found 3rd edition was to much paperwork even as a player so stayed away from it and Pathfinder. never even looked at 4th edition figuring it was a waste like 3rd was to me at least. I tried 5th edition back in the playtest and was like it's back and I am hooked. I really like what they did with the game, and with D&D beyond I buy all the books, but I do an actual order from amazon for a dead tree version for the rulebooks, but not the adventures.