Ensure you have the right spare tube when you go riding.
I went on a mountain bike ride with Mary tonight, and got my first flat in a couple of years. No problem, I whip out my spare tube and my pump... the tube has a stem that's too short.
Huh? Well, if you recall, I got a fancy rear wheel to replace the other fancy rear wheel that I got because I've had problems with rear wheels in general. Anyway, the rim has a deep-V cross section, so you need a stem that's long enough to poke out. Turns out, my spare wasn't long enough. I had actually thought of this situation and bought a valve extender, only it was at home in my toolkit.
I could have taken the tube off my front wheel and used it, but at this point I decided I was only 3 miles out and I could just jog back. So I did.
I'm still trying to figure out how I got a pinch flat with my fancy full suspension. Unfortunately, I can't blame it on big air...