If you have a friend to help you, doing an assisted bridge can help with gaining flexibility to aid back bends.
You do this by laying on the ground in front of a partner with your head a few inches in front of their feet. Put your hands up and behind your head and hold onto the partners feet. Bring your knees up and plant your feet firmly about shoulder width apart on the ground. Now your partner bends down and puts their hands one under each side of you just under your armpits. Now push up into a bridge (some people refer to a bridge as the crab position). Only push as high as you can without feeling pain. The partner should help you take your body weight until you have built up the flexibility and strength to hold your own weight. Hold this shape for a couple of minutes and then gently lower back down. Now it is important for your partner to assist you in a back stretch so still laying on the floor pull your knees up to your chest and your partner should come around to your foot end and apply some gentle weight to your knees. This should stretch out the back muscles and feel nice. If it hurts they are using too much weight.
Repeated practice of this will increase your flexibility and back strength.
I am so glad you mentioned this one. I had been meaning to get this and forgot about it! I have heard awesome things about this dvd from alot of people!
I teach gymnastics and to prepare my girls i have them do bridges in sessions of 15 seconds. I also have them when they are in a bridge rock back and forth to stretch out all the muscles and it also helps for flexibility to be able to kick over from your bridge. also stand next to a wall and walk your hands down it each time further and further.
hope that helps :)
It also helps to drop from the bottom up, not from the head down. Lay back one vertebra at a time.
You can do chest rolls or hoop behind the body to help you develop back bending flexibility. You can also do lasso (or halo or whatever you call hooping above your head) and stretch back as far as you can in a stall with both hands and in both directions.
Finally, you can back up to the wall and practice walking down it. You can also push up into back bend from the floor and then practice straightening your legs. Cobra pose is a good yoga pose to practice also.
Hrmmm...doing downward facing dog could help you build up more arm strength, and it's a lot less scary to try out if you aren't sure of your strength than a bridge ^_^
You don't want to ever push yourself too much. What I do is spend a little time breathing at whatever length (stretch) is comfortable, and then on my next breath in, when I am ready, try to lengthen (stretch) just a liiiittle bit more. If my breathing is tight at that point, I know I'm not ready for it. Just keep doing what you can do, and eventually you'll be able to do more.
Some people are naturally a bit more flexible than others, so it may take you some time...but you'll get there! the last thing you want to do is push yourself and end up hurting. It's not worth that!