Learn how to make a bowline knot. You'll never realize how often you're going to use that. If you need rope, a ladder or an extension cord, always buy more than you think you need. The fact that somebody doesn't have a long enough extension cord means that they don't put together an event for their kid because they can't get power out to a certain area. More people are defeated by blisters than by mountains. It's usually the little things that make something stop more so than the great big boulders that are in their way.