ethanshredzYup, two biggest things to focus on are getting your skis all the way to 90, and putting pressure on the base of your front ski. Once you've got those two things figured out, you'll be greasing every rail in the park.
This, also taking some speed in is helpful even though it can seem scary. Also the angle you approach the rail. I've watched people hike a rail and keep failing at it and drawn them a line to follow and they got it right away.
Just don't overthink it too much. Hike the same rail for a bit if you can. It will be easier to pinpoint what you're doing wrong. Which side are you coming off, how much speed did you have, how much did you pop, were your skis full 90, where was your weight? If you hike the same rail it takes out some of the variables so you can focus on what you specifically were doing and try some different things till you grease it. Find a low rail that you aren't particularly scared of as well. If you feel comfortable on a feature it's easier to fully commit.