1. Backside 180s are all about the windup. They're also kind of tricky because you can't really see where you're going.
2. When you start your ollie, you should start looking down at your board.
3. Once you ollie, you should start turning your shoulders slightly backside.
4. Suck up those legs, and start using your back foot to "scoop" the board around.
5. Now you'll start turning your board faster. Remember to turn your shoulders and scoop with your back foot.
6. Extend those legs and turn the board back all the way.
7. If you successfully turn all the way, you don't have to worry about screeching to a stop (If you don't do a full 180, you'll end up flying backward onto your butt).
8. Notice that you'll still be looking down at your feet for the landing, too.
9. Now you can start looking where you're going again.