The Crucible is actually rather easy. All that you have to do is out cheap kill your opponent. Pack a fusion rifle or shotgun, get a rocket launcher with lock on rockets, use your super liberally and use your primary only when you absolutely have no other choice. Also, be sure to grab those special ammo cases even when you don't need them just to keep the other team from being able to resupply. Do these things and you'll feel cheap as hell but you'll top the leaderboard in the Crucible all day every day. This is not a PvP which promotes gun skill. So take any concept of that out of your head and throw it away. Although if you can aim properly and do run into a guy foolish enough to get into a primary battle with you then you will do well there too because most likely they won't be able to aim properly. Now you can play the Crucible sober. You just won't necessarily find it fulfilling.