Find a flat, level area with a nice, level wall about 7-10 meters away and aim the beam cutoff at about the same height as the lamp itself so the top of the beam is more-or-less parallel to the ground. This will get you in the ballpark and you can adjust up or down a little bit to suit. I have the B&M IQ Cyo Premium and like the cutoff a little bit above this, not so much it irritates oncoming people on a narrow MUP (I've personally asked people if my light was bothering them, which it thankfully wasn't) but enough to throw the light a little further.