First thing, is to get the gearing right, so you dont burn up the motor. General rule of thumb, your car should reach top end speed at 3/4 of the longest straight. If it dont hit max speed, use a smaller pinon. If it hit max speed earlier than 3/4, use a larger pinon.
You should cut the comm on the motor with proper intervals. The frequency depends on which kind of 540 motor you got (turns). And sometimes it needs new brushes too.
Batteries is a chapter in itself. First of, you need a good peak detection charger. If you're running NiMh, or is planning to do, you should get a NiMh ready charger.
Further battery care depend on the type of cells.