Replying to Boot problem... +karma to help

soooo here's the issue. my whole life i've been stuck getting boots from second hand stores because its the only ones my parents will buy me since my feet are still growing. well, winter's coming, and surprise i've grown out of my old boots and need new ones, which means more second hand store boots (woohoo...). since i have no way around getting this kind of boot, any1 got any words of advice for picking some out? should i get them heat molded so they're more of a new/good boot or should i just find one that fits and go with it? remember, second hand store... so not many outstanding spk's or kreations or w/e haha

thanks guys