A variation on the same rules I teach my boating students:
Assume the other guy is less skilled than you and give plenty of room to the other guy.
If someone cuts in, assume they feel the need to go faster than you and drop back to give them room. Courtesy counts.
My personal mantra: My gonads are between my thighs, not my ears. Let the other driver be the idiot.
Mass counts. Keep out of the way of the pros.
Two objects cannot occupy the same space at the same time. If they do, it gets expensive fast.