Archery is a humbling sport.
I don't think there is a person out there who thinks "I'm a good enough shot." When a bow is brought into the equation, this is definitely the case. Here are some tips to help your arrows fly true.
1. Start running
Lower heart rates has been linked to better bow shots. You're able to calm yourself down when that big buck walks in and hold steadier, even while practicing. If your resting hear rate is lower you are that much better off. The best way to lower your heart rate is with cardiovascular activity; the best of these is running.
2. Practice the long shots
I won't shoot at anything with my bow that is beyond 40 yards, unless it's a target. Shooting and practicing the long shots can help you immensely with shots in range. When shooting long distances you are focused on holding your anchor points, making sure your stance is correct, and you hold until the arrow hits the target. Even the smallest mistakes at long ranges make to big screw ups on the receiving end. Long shots force you to focus on the basics most archers have forgotten about.
3. Check the bubble
Invest in a bow site with a bubble level. When shooting over longer distances any margin of error can put you off. A site level keeps you bow vertical. With close ranges it ensures your form is correct.
4. Push ups and weight lifting
There will come a time that you will have to hold your draw for too long. Right now you can decide how long is too long by strengthening those shoulder and back muscles. Push ups are a great way to start with kettle bells being the best. In fact follow this workout if you have access to a gym.
5. Don't trade in accuracy for speed
If you find that you can't get tight groups, try tuning your bow down. If you shoot better, leave it tuned down. Check your regulations to see what the minimum weight is. If you have to pick, choose accuracy over speed.
6. Float your pins
It seems contradictory to everything, but let your pin float in the area of the bull and squeeze. Your groups will tighten and you will focus more on watching the arrow instead of holding the pin perfectly still.
7. Shoot from your knees or sitting down
In most cases you won't be able to get your form perfect when you're hunting. Practice in positions you will find yourself in while hunting. If you sit in a treestand practice your shots while sitting. If you are practicing a spot and stalk practice from your knees. Both positions are just different enough to warrant practicing.
8. Let the release surprise you
Just like with a gun you should slowly squeeze your release instead of slapping at it. This prevents trigger panic and will stop knee jerk reactions. Practicing this while floating your pins will make you shoot tighter groups in no time.