Roll up to the rail with it aimed between your legs.
 Dont be scared to come at it straight on
JUMP!
stand straight up! Keep the rail flowing under the centers of both feet.
 This part is crucial... LOOK AT THE END OF THE RAIL. Dont take your eyes off the very tip of it.  This helped me so much. I would always slide off half way until I started staring at the end of the rail.
this works no matter the rail shape. S rail, DFD, Round or flat... your gonna end up where your eyes are aiming so just stare right thru the whole rail.
Also it sounds kinda silly but "anticipate the slide". A lot of times I would feel like my skis weren't gonna slide once I was on. This won't happen. Everybody can do these rails, thats why there is so many of them and no lifegaurd watching over each one... bcs everyone can do it with the equipment they have no mater the price.
I once saw an amish lad with some real old alpine K2s absolutely shredding rails.
 You can do it OP. This is your year!!!!