Best option is to use slime in your tubes.
http://www.slime.com/index.php?p=view_category&category_id=3
It's basically a self-sealing layer that will both prevent and repair - it'll close up punctures as the wheels turn, and usually without losing air pressure.
It really does work - I had 2 punctures in 2 days this time last year (without slime in my tubes). In the year that has followed (estimate about 800hours in the saddle), with slime in my tubes I have had no punctures at all - even though I've been over plenty of glass and other nasties that would otherwise be deserving of such a thing.
Definitely recommend it.