Hip firing a snipe-gun is a deadly, but tough skill in GE for most players to learn. Best way to develop your skills with this is to play run n' gun on archives with a laser toros (or similar gun). You'll get used to where the reticule goes as you turn. Aiming center-mass is always your best bet. I've also found that increasing the size of your "dead zone" in your settings makes it a bit easier to hip fire a sniper rifle as well, as this provides more screen space to turn your gun without turning your view. Some players argue against equipping "snap shot" on your sniper, but I find that I get more accurate shots when hip firing snipers when I do use it. My go-to loadout when I am looking to mess around with hip fire sniping (which is rare in and of itself) is the following:
Toros, kunara, ext mag, LF, SS, Laser.
Hope this helps!