You have several things going on. First, your form most likely isn't as consistent as it needs to be. Focus on doing the same thing every time. Second, you need to paper tune the bow. Head to your local pro shop and get it tuned up. The arrow needs to come off of the bow as straght as possible. Poor tuning is exacerbated after you install wings on the front of your arrow.

Yes, mechanicals do work, if you are producing enough KE. Dan up there gives good advice, though. Magnus Stingers are great, and fly like darts from a well tuned bow. Though I admit, I have a couple of arrows in my quiver tipped w/ Rocket Hammerheads, I use those strictly for turkeys. I use Stingers for deer.