I Really Need Some Help

Here's the situation. I would like to get better at the Crucible. I'm not really talking about K/D ratio. I just want to actually be a viable asset to the team instead of another target for the enemy team. I'm a level 31 Warlock who can't seem to hit the broad side of a barn, much less a moving target. No matter what sensitivity I put my controller to, I seem to be unable to get a pin-point shot. Once the gun is firing (no matter the type) it seems like the gun is going to go EVERYWHERE ELSE but where I put it. If my try to make a slight adjustment to a target that strafes, my controller seems to scream "YOU WANTED TO GO AAAAALLLLL THE WAY TO THE LEFT RIGHT????!!!" My melee is TERRIBLE!! No, I'm serious. I have been killed by other warlocks with ONE HIT but I cannot EVER seem to do that to anyone, including lower level warlocks. My melee charges fairly quickly, so I'm not sure what it is. I really don't want to go for the tired tropes of "The game is cheating" or "The other team is cheating" so I'm going to assume it's me. Once in a while, I'll be on point with about 12 kills and 5 deaths. (for me this is fine). But most games, I have about 25 assist, 4 kills, 9 deaths. I use a range of weapons because nothing has worked consistantly for me since I've been playing. However I have an Ice Breaker, Suros Regime, Serpentine Rapier, Badger and a few other max leveled guns and they offer me no increase of kills. I would really like someone to give me some tips. Is there a way to improve my aim on the PS3? Besides the Thorn (which I don't have) what guns should I be using? I say the thorn because I have been killed today alone by a LOT of Thorns in about 3 shots. As a dad who works most of the time, I really don't want a game I paid 100 dollars for to just be another game that I have no chance at getting even half-way decent at. Thanks for any assist with this.