Stand near a wall. Put one leg behind you up on the wall and walk toward the wall into a split so your legs split on the vertical face of the wall. Eventually with a partner or by yourself, try to arch up and hold your torso up while maintaining the split.
Know the cobra position in yoga? Work this so while you're doing it you can bend your knees back to your shoulders and beyond.
Lay on your chest and raise your legs behind so they curl on top of your shoulders, then work it beyond. This will eventually turn into a chest roll, too.
Just some ideas.