It wouldn't count as a DIY then. 
That's a very valid question. It's a balance. You want to aim your headlamps(not at the same spot as your halogens) to give you the best visibility but not so high as to blind oncoming traffic; that is dangerous for both sides.
The high beams thus help in this regard as they shoot the light way up from the cutoff.
From what I have observed. The low beam has to be aimed higher than the original halogen output of your car. Also, aim the left headlamp higher than the right one. That will give the best visibility and still not get in the eyes of traffic.
Another unexpected situation occurs when creeping up behind pedestrians. Because there is almost no glare from these projectors, the pedestrians do not notice there is a car behind them due to the cutoff being below eye level.
If you stand in front of my car and the headlights are on and you look at the headlamps from above the cutoff you won't even squint your eyes.
@sha2eb: What dav111 said is accurate.
