Congrats on the new car. Right now, I wouldn't really do any upgrades at all until your skills on track have improved enough to warrant going faster, stopping sooner, cornering harder etc. You just bought a new car, so why wrap it around a tire wall? You have the luxury of having bought this car, at the end of its production cycle where we've all done our mods, and understand how the car functions. Just get into the novice group, get a good instructor, and have fun. When you feel like you are up to the pace of the intermediate group, and can hang with them without an instructors help, then come back, and ask me or any one of us, and we'll be more than happy to give you a list of mods, that you can do all at once.
E90 335I: FBO +wavetrac LSD
E92 M3: K&N, V1, Yokohama AD08