Start trying this trick on a target you can easily 180 over.

First of all everyone thinks that it's easier to do this at a big angle. NOPE this is not a good idea. If you come parallel with the target you only have to do a 90 instead of a 180. If you still think you should come at a bigger angle the try a lower target. Once you are comfortable with coming parallel with your target Ollie forward like a F/S 50-50 but turn a F/S 180 while jumping over your target. When your 90 with your target extend your feet and prepare to slide. Keep sliding to the end and come out anyway you like. Just do a normal B/S Boardslide when you have started sliding.

Good Luck!