Weekly practice doesn’t have to be a chore, shooting a few dozen arrows 2-3 days a week can really help you stay tuned in to your equipment and form. I like to start in June. Also practicing at different types of 3-D targets helps get your eye used to focusing on different kill zone shots. And when setting up targets try different angles, quartering away, quartering to and of course broadside. I like shooting at a lot of different distances. Practice shooting at longer ranges than you would ever take while hunting. This will help you become more steady for those closer shots during the season. This will help with your confidence.
If you get excited anytime you are getting ready to take a shot on a animal, plenty of practice ahead of time will give you the confidence you can make the shot even with some buck fever. There is nothing wrong with getting excited, it should be expected. But the goal is to be able to control it. Easier said than done when Mr. Big comes walking by.
Consistent practice can help you in your distance judgment and let you get comfortable with yardage. There are also some great rangefinders available that really take the guesswork out of it. If you don't have a rangefinder, time at the range will make the difference when "the shot" presents itself. If you are not good at judging yardages and do not have a rangefinder, don't worry. I know a lot of people that place different colored ribbons and set yardages around their tree stands or hunting blinds. Then you just have to remember which color represents what yardage.
Consistent practice in the pre-season will keep you familiar with your equipment and anything that needs to be fixed or updated. The archery stores always tend to be busy right before the season starts with people that just started shooting and discovered they need a new string or other improvements or repairs. Practicing all summer long will get you confident with your equipment and this confidence will let you know when something is wrong. This will give you the time to discover what will work for you way before the season starts. Nothing worse than having equipment malfunction or breakdown right before or during season. Being in tune with your equipment may prevent this from happening.