Here's a good way to know if you are packing either too much or too little before you go into the actual wilderness: 1). Make out a list of everything that you think that you want to take. 2). Pack it all into your backpack and carry it fully loaded, up & down your local football bleachers for a couple of hours. 3). Then unpack it and make camp in your yard for the night. Sounds crazy, but this does teach you about the amount of weight that you can handle going in, your fitness beforehand and it is all in a safe and convenient spot. This is called practice and believe me, you can never do too much practice beforehand. Remember, with a little luck and skill you will come out with a heavier pack than you went in with.
A word of caution about GPS units: a GPS is excellent except when the batteries die or you can't get a signal. Believe me it happens a lot! Learn how to use both a map and compass effectively beforehand and bring them.
Talk to a nurse or doctor as to what you should take for first-aid supplies based on the hunt you are planning and your own health concerns. There are a lot of survival materials available. Read as much as you can. This will help you to prepare your list as well.
Pack some spare items: Batteries, Compass, Knife, Matches, etc.
Lastly, prepare a hunt plan, give it to someone you trust beforehand and you must stick to it! It's easy and tempting to deviate from your plan and area while chasing wild game, but what happens if you get hurt or lost and someone needs to find you?