As you approach the railbring your feet together to jump off both because this makes it easier to rotate when you are in the air

As you jump over the rail make sure that your weight is evenly distributed over the rail, with the twisting momentum from the jump still rotating your body

As your body is beggining to rotate keep your feet together and bring your knees up to increase the speed of rotation

You have to release your hand because your body is now over the rail, and doesn't need that support any more. To speed the rotation, you can look over your shoulder into the direction of travel.

finish your twist whilst you are on your way down and when you landbend your knees, although it's not really needed but i do it anyway