First, set your body, including your shoulders, parallel with the slope. Once you achieve that, do the same with your swing. Here's how:
Step 1: Take your address with the ball positioned an inch forward of where you play it with the club in your hand. To know for certain that you nailed your posture, line up your club with the buttons on your shirt. If the shaft points at the ball (not in front of it), you're solid.