I just put my reticule where I expect head to be at height-wise, then strafe left and right for the most part. It's what I used to do in Halo. I guess for a little clarification: I lead my targets, I put my reticule where I expect someone to be after a previous observation or just because I expect them to be there depending on the situation of the game I'm in. Known sniping spots, for example.The minute changes are done with strafes, as it's easier to predict where your reticule will be with a straight line rather than by using your aiming stick, because you might end up flicking it too far, though I do that in hectic situations, mostly in Trials. Twitch aim has worked out well too, but I know I need more practice.