oh man, and this whole time I was thinking andy parry type ski slides. WHUPS
yeah I try not to think too much going up to the rail. I know that doesn't sound like much, but if you don't think about slipping out it probably won't happen. I had the WORST time with slipping out last season. This summer I had a setup that really really helped me.
go to home depot/menards/lowes or whatever, buy a 8 - inch wide pvc pipe (10 feet long, they usually are less than 30 dollars) and set one up in your yard this winter. Just try and try and try in a safe environment, and eventually you'll get it.
It is SO fun.
Just try to stay even, weight on front foot, don't think too much, and have speed. Come at the rail straight and confidently and then commit.