Always, always respect them - never think you "know" a mountain!  Every time you go over it, the situation is different. Your load changes, the brakes are in a different condition, you probably have a different trailer, anyway, the weather changes, etc, etc!

When climbing a mountain grade, unless you're lightly loaded or empty, chances are you'll lose a significant amount of speed. Move over to stay out of the way of other traffic. Put your four way flashers on when moving much slower than other traffic.

Go down the mountain in a low enough gear!!!   It is far easier to upshift on a downgrade than to downshift on a downgrade!!!!!!

Never, ever, never go down a grade in Neutral.

Do not use the jake brake (engine retarder) when road is wet and especially and never when it’s slick. Do not become "spoiled" on a jake brake -- they are mechanical and can and do fail. If you've learned to drive in the summer and have only went down grades with the assistance of a jake brake, in the winter you will be at a disadvantage. The first time you descend a new mountain grade, try it without the jake so you'll know how to do it if it ever goes out or if it is slick and therefore, useless.

When climbing a grade when it's hot, watch your temperature gauge closely. If you have a manual engine fan, you may need to run it. It decreases power, but it’s better than overheating.

When descending a mountain grade, you could try turning the engine fan on also. It takes power from the engine. It won’t help much but every little bit counts!