[e90pilot]

For tire pressures, check to see how far down the sidewall your tire is wearing. There's a little triangle on the tire. If your sidewall is wearing below that, add a pound or two of pressure. If it's not touching the triangle at all, let a pound or two out. It's not a perfect way to do pressures because camber will affect this but it's close. Cars aren't as sensitive as bikes to tire pressure.

If you're in beginner group, make absolutely positive anyone you pass not only gave you a point by, but is in a position to let you by. Example: even if someone points me by in the Corkscrew at Laguna Seca, I don't make that pass. Also, I don't see a reason why your 335i can't be in advanced eventually. I drive my 325i in advanced group with two of the three groups I track with. You can have a slow car as long let people by. I've done track days with 100hp Miatas that I catch on the straights by 20mph but they KILL me in the turns by 20mph.

Some other little things, make sure you clear out your trunk, back seat, door cards, etc. Check for crap under your seats as well. Hook up your tow hook to the front. If it's cold, gloves are nice. Most places don't allow shorts so ware pants even if its gonna be 100F.
I'm sure someone can add something else. Have fun. Track days are a blast, but I'm not sure it'll be more exciting in a car than on a bike.