Black attack,
Brown to the ground.
Make yourself look large and don't run from a black bear.
For a brown bear, fall to the ground with your arms wrapped around your head and your stomach to the ground. If, when the brown/grizzly flips you, keep rolling until your stomach is facing the ground. Keep your arms on your head to try to stop it from biting your head.
Run downhill, not uphill. Bears can run faster uphill due to their geometry.
Don't think you can outrun a bear, which can run as fast or faster than a horse (briefly, in spurts).
If you shoot a grizzly in the head, you'll likely just piss it off. Very thick skulls.
These are the tips I remember from living in Alaska and Minnesota.
One last tip. Carry small bear bells so you make noise and don't accidentally walk up on a bear unannounced. How can you tell grizzly poop from black bear poop? Grizzly poop is full of small bells. 😁