Help?

I'm probably not the one to give advice but if it is not an urban rail then hit it straight on, pop just enough to clear the gap, space your legs shoulder width apart or a little wider. Face perpendicular to the rail but turn your head and look towards the end of the rail.

Easier said than done, I am still learning to do it consistently but that is what most of the better NSers say. Oh yah, and hit it with decent speed. Speed is your friend.

What problems do you have with rails? Just pop, turn 90 degrees(don't just tweak your legs and have your body still facing forward), land evenly, keep your weight centered in a shoulder-width stance(it helps to try putting a bit more weight on the leading foot to avoid sliding out), and just slide off. When you get the basics you can learn to scissor to properly keep your balance on rails and prepare for spinning off the rail.