One of the quickest ways most of us could improve accuracy would be to shorten the draw length of our bows. Most bowhunters shoot a bow that's just a little too long for them because they're trying to get a little extra speed. But speed doesn't do anybody much good without accuracy.
To see what I mean, perform this demonstration. Pretend you are at full draw. Physically do this -- minus the bow. Draw as if the bow you are shooting has a draw length two inches too long for you. Notice how tight your muscles and joints feel? Now pretend to shorten your draw length, and you'll feel everything relax. Relaxation is good.
This exercise demonstrates why it is much easier to shoot a bow accurately with a draw length that is too short as opposed to one that is too long.
The ideal draw length for you is the one that allows you to anchor in a comfortable position, with your bow arm elbow unlocked (slightly bent) and your release arm elbow and forearm pointing straight away from the target. If the release arm elbow points left or right, your draw length is too long or too short.
In order to shoot a bow accurately, you have to be relaxed. Remember, your entire goal when shooting a bow is to allow the bow to shoot the shot. If you don't interfere with the bow, it will shoot the arrow exactly where it is aimed. The more tense you are, the more likely you are to interfere with the bow and cause it to shoot the arrow off target. So shorten your draw length to ensure a relaxed body -- and maximum accuracy.