It's essential to get the rotation of the bulb correctly set before aiming. The left side of the pattern is perfect for not blinding oncoming drivers (if aimed correctly), but the right side has scatter, and it's angled and quite high, making roadside signs pop.
The left side to the middle is what's important for aiming. For most cars, this is two inches below the distance between the ground and the dimple on the light housing @ 25ft from a vertical wall.
Set the rotation first, then aim at 25ft, paying attention to the obvious horizontal line L to the middle, and you'll be dialed in.
