I developed bursitus and have daily stretches for my hips. They do help a lot with riiding!
1) lie on stomach (I grab one of the rugs to put on the floor first), bend one knee so calf is straight up & down. rotate leg left & right. this loosens up the hips something incredible. I do this one 10x per leg.
2) sitting on flat surface (the pony's rug gets a lot of use), feet on ground, knees in front of me. hook one ankle over the opposite knee, pull thigh back till you feel a stretch in your hip. I do this one for 30sec 3x per leg.
3) standing by a wall or some such for balance; wall on right, cross right leg in front of left, bend left hip until you feel a stretch (then switch). I do this one 30 secs 2x per leg.
Now, these were given to me by my physical therapist. and I'm not sure how much a non-bursted person should stretch 'em. but they help a LOT with my hips feeling sore after riding--I stretch before & after.