Well it's your choice on where you want to start and where you want to end. I'd say most people would recommend a RMM (rear motor mount) to start, it helps clean up the shifting. If you want a more comfortable ride, a 16" wheel and thicker tire will help with that. For style it's personal preference and there are a good amount of options that can make your FiST yours!
If you're looking for more power, you can get a bit more fun out of the car with an intercooler, air filter, AP, and then a tune from either stratified or dizzy tuning.