Probably old hat to most here, but I always carry a couple forms of fire starting (bic, magnesium starter, and matches) and some fuel(vaseline soaked cotton balls in an old film canister)....I've yet to need to make an emergency fire, but if I ever do I like knowing I will be able to.
For "undercarriage" issues, I used to use aquaphor (and it works) but now I use my homemade beeswax/coconut oil lotion bar. It's a harder consistency at room temp, but melts at body temp. I mix in a little vitamin e oil to help the skin.
And, finally I'll reiterate the importance of a sound, cool, collected mind. If you get into a hairy situation....it will be your mind that gets you out. Learn how to navigate and orient really well with a map and compass. Learn about declination, triangulating your position and measuring distance from maps. Knowing where you are on the map makes it a whole lot easier to figure out how to get to where you want/need to be.