One of the best stretches I know for shoulder flexibility is to do a bridge and then put your feet together and push your legs straight (so you're pushing over your shoulders). Also, can you stand up from a bridge? If you can't, it will be harder to get the front walkover. I'd work on that by doing a bridge by a wall and walking your hands up the wall to stand up. Make sure you're pushing your pelvis forward and using your thigh muscles.
Also, (and this is oven overlooked, but really makes a difference) are you pulling your head up? You want your head to be the very last thing to come up out of a bridge or FWO. If you pull your head up too fast, you are changing the whole curve of your spine and you will be working much harder to stand up. You should keep your head back and come up in this order - pelvis, chest, chin then straighten your head. It also looks so much nicer. I hate seeing people pull their heads up first, it looks so sloppy (from a gymnastics background, where form is stressed so much)
