Easiest way to get a decent setup is to just buy one (with in-game credits). Lots of cheap or free ones to choose from. If you don't like it, just get another one. Otherwise you can spend a lot of time upgrading, tuning and test driving. Tuning has quiet a learning curve when you're starting out. Just started messing around with the drifting... got my "Tire Shredder" tag last night.
1000hp 240sx makes it pretty easy.