Hey Man, I have the exact same car and it all depends on what you want to go for. If you are looking to smoke other cars, start w/ the engine, but if you wanna make it look good, do that first. I personally would deck out the engine first. A good starter is a High Performance Intake. That gives some good horse power for not a lot of money. Also, a single in, dual out muffler will give you some horses too. Underdrive Pulleys are a good choice. If your car is automatic get a shift improver kit. Granted doing all this stuff won't beat a Z28 or SS, but it'll sure kick the crap out of some rice burners.
As for looks, I'd say lower it. The ground effects look good, but I think if you lower it, it looks just as good and it's cheaper and you'll get better handling if you do it right. There are some cool looking wings and of course a awesome looking ram air hood will definately dress it up.