Check it twice, and be sure it works!
My dad always made lists of stuff when I was growing up on the farm. Mostly lists of chores for me, but also lists of parts needed, broken stuff that should be fixed, cows that were missing, and when to grease the tractors. I dreaded those lists 'cause they severely cut into my spare time goofing off, but now that I'm starting to forget stuff, I'm finding the value of the list, and have been making one recently that should be really useful for your next wheeling trip.
When you get off the Interstate and start creeping down the backroads, you need to be ready for anything. You never know when a three-hour tour can turn into a "stranded in the woods with a busted rig, under cloudy skies, with a long hike from anywhere" type of dilemma. In such a situation it is most important to stay calm, and the security of having a few supplies on hand can help tremendously in keeping your heart rate down, and the question of "How am I gonna get out of this mess?" at bay. So here is a basic 4x4 checklist. Things to inspect before you hit the road; things to bring along, whether going for a weekend or for an hour; and things that sometimes slip your mind when you are too excited to get to the dirt. Here's a hint--when you are loading up the truck, have your wife, kid, dog, or neighbor check off everything on the list as it goes in the truck.
When properly prepared, and traveling with a come-what-may attitude, you should be able to get through almost any obstacle that should arise. Remember that the longer you plan on being out there, the more stuff you should probably bring. Doing a 20-minute competition course means making sure you have fuel. Traveling from the tip of South America to the Arctic Circle means bringing everything on this list and then some.