I used to hold the hoop in one hand --very awkward--and it ended up being practically vertical to my quilting hand. Then I got a hoop that sits on your lap and it's very level--it made a big difference for me. Also occassionally, I'll quilt without a hoop and, yes, my hand starts to hurt. Then I'll release all the bunched up quilt and just hold a bit of the sandwich nearest to where I'm quilting. I saw Suzanne Marshall demonstrate that technique on The Quilt Show.
Quite frankly, I'm starting to think about learning to machine quilt 'cause my hands are suffering.