i installed some tire liners, http://www.rei.com/product/787739/st...rs-700-x-23-25, and haven't had a flat in about 8,000 miles. they have saved me from at least 10 flat tires.
every time i take a rest i do a quick check to see if anything is stuck in my tires, and i regularly check my tires for debris embedded in my tires when wiping down my bike after a ride.