Gain Speed.

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 comfortable with the trick..)

Perform a clean ollie.

Immediately upon takeoff, 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.

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.

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