Can you hit a 6X6 piece of cardboard 100% of the time at 10 yards? If you can, you simply don't take any shots beyond 10 yards.
One thing I highly recommend you do is get a copy of Byron Ferguson's "Become the Arrow" book.
Another is to not do all your practice shooting at a target. Stick judo points on a couple of arrowsthen get out to do some stump shooting. Pick out a worthy target, be it a clump of grass, dried up cow pie (watch out! Some of 'em can look dry on top but still be a little 'green' in the middle[8D]) or even litter, like beer cans or plastic pop bottles. Shoot at them from wherever you see them and see how close you can get. Then pick up your arrow and choose another target.
Tip: When I go stumping, I always carry a plastic trash bag to put the litter in after I shoot it. The forest rangers on thepublic landlove me.
I don't know about you, but lots of times when shooting at a target face, I get all wound up in trying to be a perfect shot. That gets me tensed up and makes me shoot terrible. Getting out and just playing bows and arrows, you relax and, for me anyway, shoot a lot better. Plus, it gets you used to shooting in the woods and that's a major advantage for a bow hunter.
This is all assuming you know your arrows are properly spined for your bow and you've got the bow tuned.
Always keep this old saying in mind: Aim small, miss small. If you aim at the entire piece of cardboard, you can miss the cardboard. So, don't aim at the piece of cardboard, but at a spot in the middle of the cardboard. Take a magic marker and put a dot in the middle of it, and aim at that. You might miss the dot, but you'll hit the cardboard. When you aim at a deer, don't aim at the deer, but at a hair, afold in the skinor maybe a leaf stuck to it's hair where you want to hit.