Like Kim said, it's always good to carry a tire pump and at least a patch kit when you ride. Yesterday, I got a flat, and there I was having to fix a tire on the spot. I really recommend the CO2 canisters that you can use to inflate your tires. They are available at most bike shops. The initial investment isn't much more than a good pump, and it inflates your tire instantly, so no standing and pumping. Just load your CO2, and you're good to go! I also carry a multi-tool, but this won't do you any good if you don't know how to use it! Take some time and become familiar with your bike. Learn how to make adjustments that may need to be made on the trail.  Also, always take plenty of water (I sometimes use gatorade or endurox during a race) to stay hydrated.

Finally, A good rule is to always do a quick once-over of your bike before you go for a ride. Making sure your chain is lubed up and your tires have enough air in them are really great ways to minimize your on-trail bike maintenance!

Happy Riding,

Cortney