Gymnasts! What are some exercises I can do at home to strengthen my arms for bars?

What can I do at home to strengthen my arm muscles so that I can do hip circles and pull over and such better?? Also when you first learned your back hip circle did you get bruises on your hips? When ever I do a bunch of casts I get REALLY bad bruises on my hip bones and it hurts. I have two massive bruises on each side from practicing hip circles.Gymnasts! What are some exercises I can do at home to strengthen my arms for bars?
Chin-ups, push up, casts, skin the cat, basket hang and things like that are really good to build up arm strength but to do back hip circles you also need stomach muscles so things like sit ups, v snaps and dish are good for that.

I used to find that I did get bruises on my hips but you get used to it over time so the bruises will most likely fade.