If you plan on keeping it auto I'd do the following...
1.Intake (AEM Cold Air), Headers, Catback Exhaust.
2. Do what Jschmid said and drop $1500 on Rims, tires and a lowered suspension. Personally I use, Eibach ProKit Springs, KYB Shocks And Yokohama AVS ES100 tires 215/45/17 (You cannot go wrong with yokohamas)
3. Don't rice your car out with a stupid aluminum wing or some ugly body kit or Altezzas...unless you happen to like that style.
4. Keep it clean...
5. Get a job. Cuz with $1500 you won't be able to afford all of this stuff