I honestly think you should stay away from the railey until you have some solid edging as you approach inverts. Solid edging for some of the basic inverts out there (tantrum, backroll, heelside front) will give you an understanding of how to position your body in different ways before attempting a railey. Seems to me lots of people have a hard time with raileys (stargaze, etc..) because the edging isn't stable (or weight control).
Start trying heelside front flip before a railey. You can almost use a railey edge for this trick. I do..
Just my two cents.