Over and over you will hear me say that your bow will shoot every arrow perfectly -- if you'll only let it. One of the biggest ways to interfere with the bow is by grabbing it before and during the shot. This twists the bow and throws your arrows off target.
You can solve this problem with a wrist sling. The sling attaches the bow to your hand, so you have no need to grip the handle. Rather, you can keep your bow hand completely relaxed before and during the shot. Without a sling, you have to wrap your fingers around the bow or grab the bow as the shot goes off -- both of which are bad news for accuracy.
Most wrist slings I see on hunters' bows are completely worthless -- they're way too loose. The sling has to be tight enough so you know it's going to keep the bow in your hand. Remember, you're trying to train the subconscious that you don't have to grab the bow.
When I'm practicing for the hunting season and also when I'm competing, I actually tie myself into the bow with a rope sling. Because it's very secure, it trains me to keep a relaxed hand. This sling is a little cumbersome for hunting, so I switch to a slip-on sling for hunting. You must determine how tight to make the sling on your hunting bow based on how fast you need to get your hand into your bow. Just remember -- when practicing, always keep it snug.