Street Style Rails
Sounds like you're nailing it now! I'l make a post anyways for some of those who haven't tried this yet.
If you have your 5050's dialled on boxes and rails in the park that allow you to ride or jump straight on to them you are ready to try your first street style rails.
Before you hit the rail, ollie off the jump beside it once or twice to get an idea of how much you will have to pop to get your self onto the rail. When coaching people, I usually get them to ollie beside the rail twice and then across and over it twice before they land on the rail for the first time, that way they are confident that they will get on top of it when they go for it.
Now that you've ollied across the rail a couple times, put your weight down on the rail as you come across, you will probably just touch the rail at this point and continue on to the far side, but that's ok!
For your next couple times work towards eliminating the angle that you are approaching the rail at. Ideally you will approach the rail at a 15-20 degree angle (almost parallel) and use your pop to move your weight sideways to land on top of the rail. Look at the END of the rail as you ollie off the jump, point your front hand towards the end (to keep your shoulders aligned and your weight forward) and ride the rail to the end!
If you are still landing on the rail and coming off on the far side, make sure you are approaching straight and don't be afraid to land with your board slightly angled against the rail to prevent you going over the other side.
If you land on the rail and come off on the same side you approached you're not getting fully on top of it. Approach with slightly more speed and don't be afraid to pop a little bit higher to land fully on top of the rail.
Hope that helps!