Recently my demo team has been doing back handsprings, front handsprings and aerials. Most people have been able to get it by now, but I'm still falling on my face even with spotting due to my pathetically weak upper body strength.    Since I'm the only girl, I don't want to get singled out as the weak link. Does anyone have any good conditioning routines for the upper body and core muscles needed for this sort of tumbling? (please!)

If you can't hold a handstand you have no business trying to tumble especially back handsprings.

Like Jereme said... work handstands, hs shrugs, etc. I would also add in dips, pullups, rows, pushups, etc. building up your total upper body strength.