Hills
On a steep climb, use a low gear - first gear for the steepest - and stay in it. Changing gear mid-climb loses the momentum you needed the gear for.
Going down is the more dangerous direction. Use the same low gear you would use to climb it and let the engine hold the vehicle back. Riding the brakes all the way down heats them until they stop working, and a brake failure on a descent is the worst place to have one.
On a narrow hill road the vehicle coming UP has the right of way, because it is harder to restart on a gradient than to hold still on one.
Sound the horn before a blind bend. On a mountain road that horn is the only warning the vehicle you cannot see is going to get.