Haynes and Chilton say:
Find level ground with a flat wall. Pull the car right up to the wall and mark the horizontal and vertical centerlines of the headlamp assemblies with tape. Pull the car back 25 feet and turn on the headlights- the area of the light pattern with the most intensity should be on the vertical lines and 2 inches below the horizontal line. At that setting, turning on the brights should make the light go straight ahead, or lined up right with both lines.
The gist- you want your regular headlights to be pitched a couple degrees down from parallel to the ground.