First, you want to be skating along at a comfortable speed - not too fast. Place your feet in the normal ollie position, with your front foot on or just behind your front truck bolts, and the ball of your back foot on the tail of your board.
Now, for a frontside 180, you want to put your back foot back just a little bit towards the heel edge of your skateboard. Putting it here will help you spin the board when you ollie.
As you crouch down for the ollie, you want to wind up your shoulders in the opposite direction than you are about to turn. So, if you are a regular skater and learning the frontside 180, then turn your shoulders to the right as you crouch. If you are a goofy skater, then wind up for the frontside 180 by turning your shoulders to the left.
