Best way to go is vulcanizing patch kits. Get a bunch of them at less than $2.00 a piece. I always carry an unopened kit with a brand new tube of glue in my tool bag. Once I open the tube on the road then that kit stays home in the refrigerator with all the other patch kit left overs that I use for fixing flats at home. I also add to my patch kits a razor blade, tooth pick, valve remover cap, and a coupula of alchohol pads for cleaning the tube. Oh, and I am also one of those guys that put the glue on the patch and the tube, then lets them dry before bonding them...

I have not had any luck using scabs, but I have known a few that swear by them...