I set up my headlight mount just loose enough so I can adjust the light height based on where I am.

I set my light slightly higher, on steady light when I'm on an open road. When I'm in my neighborhood, I aim it to about eye-height for someone in a car and set it to blink. I've been hit by a car twice in broad daylight, so I'm not going to let a driver not notice me. I'd rather they be uncomfortable for a second, and notice that I'm coming, than go easy on their eyes and let them ignore my existence.

When it comes to other cyclists/runners, I always aim my light down as to not blind them.