Step 1: Pre-Wind - Head into the jump centered on your board. Wind your upper body 90 degrees.
Step 2 & 3: Unwind and Shift Weight - Throw your arms around into the direction you want to spin. At the same time shift your body weight from centered to over your front wheel. This will help stick your front tires in place as the rest of your board rotates around them.
Step 4: Ride Out - Now you should be riding out switch. One of the subtleties of this trick is to ride out straight and not under rotate or over rotate. The faster you go the quicker you'll want to spin.
Variations: Slide 180 and Jump 180 to be covered in future Trick Tips