Make sure you are very confident and consistent with your backrolls and wake 180 backs. This trick involves mixing these two trick together.
As with all new tricks, try to first see yourself doing the trick in your mind. This will eliminate a lot of extra crashes. Now get out there and throw a normal backroll. As soon as you start coming around for the landing, pull the handle in and place it on your outside hip. This motion will spin you around backward. Now lean forward so the tail doesn't catch and you'll land it.
You can wait until you've completed the back roll before you spin around, but that method is more difficult. Just concentrate on the backroll for the first 3/4 of the trick and the 180 spin for the last 1/4 of the trick. It's will be a very akward feeling at first and is sometimes hard to envision. But, after you've attempted the trick a couple of times, you'll understand what you'll need to do. Always fully commit to the trick at every attempt. If you try to bail out, you may get hurt.
I always end up landing sideways. You might need more hang time. Concentrate on getting a bigger pop off of the wake to throw a big backroll. Don't think about the revert until it's time to throw it.
What's next? Try a frontroll/revert.