Originally Posted by Spunout
get yourself a pair of mr.tuffy tire liners.
The kevlar liners work great but they're very often like putting $1000 rims and tires on a 78 Chevette. They're very lightweight and very supple as far as tire liners go. Last I checked, there weren't very many motorized bicycle builders worried about shedding that last 2 ounces per rim. If I were racing my mountain bike on a course riddled with goatheads, I'd use them. Not racing, something cheaper.
My advice will always be to start with quality tires, something like Schwalbe Marathons once the originals have worn out. A tougher casing does more good than a puncture proof tube or a tire liner. They're not only tough but they ride well too because the casing is more supple. Slime and all that helps but I personally hate the mess and always have a spare tube and tools to repair flats.
6000 miles and counting (albeit non-motorized) on Vittoria Randonneurs, another quality tire, with only one flat and it took a box staple to do it.