well it depends on which ways you spin and grind, but i spin left and slide right foot forward naturally, so that makes a left 270 into an unnatural slide for me. there are certain things you should practice, 1st would be unnatural slides as you need to be completely comfartable sliding unnatty, else it's going to be trouble. 2nd, you should be able to 360 off little bumps, else you're no going to get around. next, i good way to practice getting the feeling is to do switch on to unnatural, as that gets the feeling of coming around the way you'll be spinning and then sliding unnatural, kinda warming you up to the pop of the lip. then you just have to go for it, start on a box with a lip that's almost ride on (or ride on if you thing you can get it around). make sure you keep your hands down, as they will throw you off balance if they're up and waving all over the place. make sure to lean forward, as you have a tendancy to lean back with 270s on, a good way to prevent this while getting the feel is to lean forward while you spin. another way to get the feeling for the spin on, is find a nice wide box that's basically ride on, then huck yourself around so that you spin on top of the box (vinnie dorian and t-hall both do this on a picknick table in Front Line). good luck!