K now grab a muscle car, switch to manual, and turn them driver aids off.
Practice in 2'nd at "locking it" at an angle. Once you've got that down nice, hop in a lvl 3 Z06, 4'th will act like the the muscle cars second, get more used to that. And then start practicing in third (more like drifting in forza). There will be a certain point where the ZO6 starts to limit what you can do on mountain roads, when you hit this point hop in either the SRT-10 Coupe, or the RUF RT-12 as they're the best and should be used to further your abilities. And once you've mastered one of them you can almost drift any car in the game.
Have fun !