snook pretty much covered the basics.
Only think I would add is the faster you learn not to overdrive the car the easier its going to be to control costs. The E46 will just blaze off the outside of the front tires with the stock setup. The tendancy of most newer driver to overcook turns just makes it worse.
My personal todo list would start with brakes and then camber for the front of the car.
Manual gearboxes, the rotary dial of cars.