Backside 720
Optional
none
Do not get confused with the name. The Backside 720 is a 360 degree spin followed up by an outside crescent or hook kick. One spin plus hook or crescent is usually referred as a '7' or '720'. This one starts from backside.
01 Standing 360
Start by learning how to spin vertically without falling over. Stand in backside stance and squat down a bit. Wind up your arms open and bring them in for the spin. Practice this until you can do it, without falling upon landing.
02 One knee up
Now do the same, but try to land with your kicking legs knee up. Also practice spotting a target now.
03 Backside 720
For the last step you'll just have to extend your leg to kick out. It should be easy if you are comfortable with the last two progressions.
Tips
There are two main problems most people have with this trick. First is balance and second is the kick. For balance you'll just need to practice spinning in place vertically. There's nothing more to it. Try to stay upright when you perform the trick.
For a better kick, you'll need to practice the kick itself. Kicking out of vert kicks usually results in crescents instead of rounds and hooks. So practice the outside crescent kick by itself.