when I used to stretch my flyers, we had a couple things we did everyday. First like someone said up there, make sure your muscles are warmed up first (aka do your straddles and all that jazz before). For heel stretches/bows i'd have my flyer kneel down with her back to me and I'd stand behind her and she would wrap her arms around my calves. Then have your stretcher take which ever leg you are stretching and hold it in a heel stretch position. This really stretches you a lot since you're on your knee. For scorps, face your stretcher and hug her around the waist and have him/her grab your leg like a stretch a pull far. Then you can do wall stretches where your stretcher grabs your leg and pushed it toward the wall.
Then of course on your own you can do splits, splits on an elevated surface, pulling your stretches/scorps/whatever, and if you are flexible enough, use a door frame! Put your leg up behind you against one side of the frame and push with your hands on the other side. That would work for heel stretches/bows as well.
I think one thing that's important is not to focus entirely on one leg. Try to get flexible in both legs and that will make it easier to pull one-sided tricks, and would it would be good to have flexibility on both sides for things like tick tocks. Also work on bridges for back flexibility cus that's really important for scorps
Go to Debbie Love's website ! She has a ton of stuff that could be useful. it's fortheloveoftumbling.com