Height is the main thing, you don't want the dipped lights shining higher than the light itself. Stick a mark on the wall at the height of your lights, and make sure the lights point under them.
As for left and right, there are regulations on where they need to point, and they are an MOT item, but as the machine said, they're pretty easy and alot of garages will do them for free or a few pennies at most.