Drivers: When you arrive at a 4-way stop intersection at the same instant as other cars, do you follow the rules of right-of-way, or do you play first-come-first-go?

I’d like to follow right-of-way, but I can never remember if it’s the car on the left or the car on the right that goes first. What if there is a car at each of the four corners? It seems to come down to guessing who was there first.