Practice. That's all there is to it. It's much more rewarding though than using a shotgun. It's just the way the maps and game modes are set up. If you play Control or Clash, that's a reason why you're having issues. Control and Clash are both 6v6 game modes, and given the small nature of the maps, it's just a cluster-blam!- and you rarely can efficiently snipe unless you're really good at it. The best place to learn sniping is surprisingly PvE (#EmberCavesFTW), or, if you really prefer learning in PvP, practice in Skirmish.