The best thing you can do to prevent flats is to not ride over debris. After that make sure you have a great rear tire with a good tube that is the right size for the tire.
My favorite rear tire is the Panaracer Pasela Tour Guard Tire 26 x 1.25 or the Panaracer Pasela [...]
Read the complete post at http://ebent.wordpress.com/2008/03/02/tire-repair-tools/