I'm ashamed to say I'm not much of a car guy, but I now own a 89 Firebird. I wanna fix it up but don't really know where to start. Heres a list of things I know. The body is in good shape other than a couple of dents on the hood and driver side tire area, and the wing in the back is breaking off. It also leaks water from the T-Top roof and the interior is kind of messed up. The starter messes up as well, where do you guys think I should start.  If you have any questions, please ask them. I really want to fix this car up.  

How do you intend to use the car? If it is for a daily driver and the paint is still good, consider one of the "paintless dent removal" services. Ask at a local new/used dealer, they can usually tell you how to find these guys. Check with a local body shop about the wing and then consider getting the paint professionally polished to bring out the full shine. As for the leaks and interior, the resto supply shops should be able to help with new seat covers, carpet, t-top seals etc.  The starter issue is easy, replace the starter with a quality Delco unit, clean all the cable connections thoroughly and have the battery tested and replaced if necessary. Most importantly, remember to take care of the issues that annoy you most before starting any major modifications, you'll enjoy the car more.
Steve  

I agree with Barney on taking care if the more annoying things first. I have 2 '88 Firebirds (One is a Formula) and a '89 *** both had their "issues". I would go with the starter so it is drivable, then the T-top seal (so the interior doesn't get anymore damage than it has to take. If I am not mistaken the Formula from'89 has the Aero wing, it is very common that they are falling apart. You can get a fiberglass one from a couple of sites online like

http://www.hawksthirdgenparts.com/firebirdformulatransamgta85-90wraparoundrearspoilernewaftermarket.aspx

If I were you I would start with mechanical problems, get the driveline squared away, suspension, then move to the body, and lastly interior. That is the way we used to restore the vehicles at the Corvette shop I worked at. Good luck and keep us posted! (I might have more info for you on the 3rd gens if you wanna know just ask!)