Play in the crucible, but run around. Use a legendary HC such as timers lash, and a low RoF high impact sniper such as Efrifeets spear. I have gotten some unbelievable kills in the crucible once I got used to hitting headshots. Skolas's head is the size of a smart car. Just shoot it lol

Solo the Exclusion Zone (glimmer farming) at level 30 with only a sniper. NEVER hard scope while you are practicing here. You need to learn to take consistently decent guesses on where your target it and learn to place your shot within split seconds of scoping in. Once you feel comfortably test your mettle in the crucible with your sniper. If you can hit a moving player, you're as good as you need to be for any PvE content. This is advantageous even if you never find your groove because it trains you to deliver one shot and relocate all in roughly 1 second. Eventually you'll find a specific rifle that suits your play style and notice significant performance improvements. You'll probably want to try your luck with a LDR, Long Bow Synthesis or Patience and Time first as these can be effective when used intelligently by subpar skilled snipers due to high aim assist ratings. From your perspective you essentially have a larger hit box to aim at. A shot that would have grazed an opponent's ear and left you killless with Efrideet's Spear will track your opponent's dome aggressively if fired from a Long Bow Synthesis. Tl;dr Find your shot with a high aim assist n00b rifle, then you can go back to your high impact rifle and wreck. Practice running Exclusion Zone like you would do a glimmer farming run with just a sniper rifle and then move on from there.

When his head reals back the crit spot is up higher even though your still aiming at his head. I recommend shooting just a bit higher