I run a lot of option and what I have found is that I need to get as horizontal as possible with my QB right before I pitch. It isn't so much aiming the pitch as getting my guy in a little bit better of a relationship with the pitch man.
When I run option from the gun, I make my first 2 or 3 steps downhill right at the defensive end/linebacker and then level off to run horizontally until I pitch or get a hole to cut. For whatever reason, I feel like the back maintains a better pitch relationship and the pitch is a whole lot cleaner that way. Instead of a pitch that goes 4 or 5 yards back, it is a more horizontal pitch and my back is able to run into it and take off. I also make sure I draw contact on that pitch, if you pitch early, it is either going to hit the defender or he'll just adjust and drill the back (or worse, you get the pitch going 10 yards past your HB).
Option from under center is a little different. Under center, I actually give depth to get a better angle for that pitch. I usually take the snap and arc about 4 or 5 yards deep before attacking the first defender that appears (usually a linebacker). Run right at him downhill and pitch off him. Ever since I started doing that, I would break off HUGE option runs.
Even if you don't have a lot of time to level off horizontally, I will try and turn my QB's body to the side before I pitch just to get a bit better relationship.
I still get one of those errant pitches every so often, but more often than not it is my fault from misreading the play than it is the game. I needed to get in a mind set where I am keeping with the QB until I absolutely cannot keep it with him any more. That helped cut down on pitch fumbles big time.