For a Toeside Ole 540's.....there's a few things to think about.
1. Grab First....if you're going to make this trick look right (aka Like Watson does them) you need to grab with your front hand...you can do a number of grabs, but I prefer mute. Remember to bring the board up right off the wake and get the grab before thinking about the spin or the flip.
2. After getting the grab, jerk the handle in hard. I usually think about pulling it right into my armpit to get some slack in the line to do the trick
3. After jerking the handle in, pull it up and over your head...kind of similar to the handle pull on a whirly bird.
4. Really try and keep your board as on-axis as possible...it'll go off a little, but the closer to on-axis the better it will look.
Some similar tricks are a mute scarecrow and a grabbed o/a 540....the big difference on this one for me was figuring out how to pull the handle in to get some slack on the line. Good luck!