For example if a car is waiting at a stop sign, or getting out of a driveway, and I have priority, I always check if the driver is looking at me. If not, he possibly didn’t see me and might go while I pass.

It happens that drivers only check for any large moving object (because they expect cars) and don’t notice a cyclist.

Basically any time a car has to wait for me to pass, and I don’t have much distance to react if it doesn’t, I make sure the driver has seen me.