Disobey Gravity

I don't know what your upper body strength is like, but I've found those metolius rock rings to be really useful. They can be put up even if you live in an apt. and can't drill things into the wall. I put them up temporarily off a metal stair case and took them down when i was done. If you live in a house you can drill one of those large training boards. anyways, i found pull-ups not that useful after you are able to do about 10 of them. Lock-offs are more useful and push-ups are very useful.