All I would say is be consistent. The best way to train for a half marathon is just get your body used to running (which it sounds like you've already been doing).
I never did more than a 5k for a race but I did 8-10 miles every day to train for them (1 miles warmup, stretchs, 5-6 miles workout, stretches, then miles or so cooldown). 10 miles is the most I did by myself though on one run.
Good luck.
That sucks. Where were you buying shoes?
I want the Salomon Speedcross. All my friends love theirs. I really liked my Minimus but after 15+ miles the trail would wear on my feet. Tried my local outfitter that carries Salomon but they only went to 12. Offered to order them if I paid for them. Not going to order something I've never tried on.