Well I just bought my 350 TPI Firebird off another member here a little over a month ago. I bought it knowing it smoked a bit. Anyway - the motor itself is a 350 Tuned Port Injected - the prev owner said the smoke originated after he had a job done on the heads and said he didn't think they did the seals right. Mainly it smoked on startup - and after stopping in traffic for example and then as soon as I'd give it throttle I could look in my rearview and see a bit of smoke. You could very rarely see smoke at idle. Now in the last week it suddenly got worse. It smokes a lot worse especially on startup. When idling, it lopes a bit due to the performance prom I have in it, on each lope it'll smoke. Also from a stop, it still smokes pretty well when I give it throttle. A lot of times if I'm at WOT, it will hardly smoke at all. Anyway - I have some buddies who are thinking it's just the valve seals. The previous owner said he assumed it was the seals as well. I'm burning through about 1/2 a quart every 2-3 weeks. If it does indeed sound like valve seals - where would I find new seals? Is it simply something at autozone or do I need to order it - and how do I know what to get? I'm knowledgeable about cars as a subject, but mechanically I'm pretty new. I've never had a car that I really felt like I could work & learn on - so any help is appreciated. I have friends who should be able to help me do the valve seals if that is indeed the problem.

Sounds like the valve seals to me, the same thing is wrong with my S-10 with the same symptoms. Mine happened after my mom drove it with no coolant in it for 20 miles though. Just go to any parts store and tell them you need the seals, they're really small and circular in shape.

Okay so do I just go and tell them I need valve seals for a 350 TPI? Or is there a specific size I need to get?

Are valve seals very difficult to install? I'm hoping to attempt this on my own but if needed I could probably get a couple friends who know their way around f-bodies to help me out.

Just get ones for your particular car.
Having the right tools is especially helpful when doing valve seals.
I've never done an f-body with the heads on the car but I have done them with the heads on the bench. Not particularly fun considering that it's easy to lose a keeper otherwise known as locks.
I've done a Grand Am with the heads on the car using compressed air. Also not fun.
Do a search on how to change them. There are several good threads on here involving your upcoming project. There are even pictures of some really good valve spring compressor tools.

Mine had the same symptoms as yours. I changed the seals with compressed air, not that bad to do if you have the right tools. However, it did not fix my problem at all. It turned out my oil rings were for whatever reason letting oil by. They were sloppy on the piston. It only had 5K miles on it also. Tore it down, deglazed and rehoned it, new rings, bearings, back together again in a a weekend, now my problem is solved. When you get new seals, umbrellas are ok on the exhaust valves, but get the "click" style for the intakes. They are hard to describe, but they are like a 1/4 tall and fairly thick. When you put them on, they kind of click on the head, something like flourelastomer or the like is what they are called.