1. Gain Speed
2. Place your feet in the standard ollie position (though you may want to put your front foot a tad closer to the nose of your board until you feel completely comftorable with the trick..)
3. Perform a clean ollie.
4. Immediately upon takeoff, you'll need to start your backward rotation, keeping in mind that the speed of your rotation need to be adjusted to suit the purpose of your backside 180. For example: if you're just doing a quickie to turn yourself from regular to fakie, you'll need to turn quickly, but if you're backside 180ing a big gap, you'll want to rotate slowly, so you don't over-rotate.
5. To rotate correctly and retain balance for landing, your entire body must turn. Explanation of how to turn is wasted breath - for everyone the process is different.
6. When you land, try hard to get all four wheels to land at once. Your weight should be centered over your board - over weighting your nose or tail upon landing could prove to be disastrous. Your shoulders should be in line with your board, your arms raised for balance.
7. Remember to absorb the shock of landing with your knees, not the lower back. And if you're backside 180ing off of something high, to avoid deck-breakage, land with your feet directly over the trucks.
8. You've landed, you're now going fakie, or backward, or switch, or whatever.