Well, as others have said, all you need is a rifle and a license to hunt... but I believe that having some other gear makes life so much more comfortable and makes your time in the woods more productive and enjoyable.
First, clothing and gear that will keep you warm if it gets cold are the most important thing! What clothing and gear depends on where you live. "Cold" in Florida is not the same as "cold" in Alaska. I am very cold-sensitive, and I mostly hunt in Virginia, where it does get below freezing, but not much below freezing. Still, I do NOT like being cold in the woods. Here are some things that I really like that help to keep me warm on cold mornings:
- Merino wool undergarments
- insulated boots
- boot blankets
- bib
- balaclava
- hand muff (I don't like wearing gloves when I'm hunting)
- lots of Hot Hands packets to stuff inside the hand muff and boot blankets
- fleece jacket
- heavy jacket
- fleece blanket
- sitting cushion
This is a "layer" system. If my boots aren't cutting it, I'll throw on the boot blankets. If they aren't cutting it, I'll throw a Hot Hands in each boot blanket. That has me covered for Virginia. If my bib/pants aren't cutting it, I'll throw the fleece blanket over my legs. If my fleece jacket isn't cutting it, I'll throw the heavy jacket over it. I find the balaclava to be one of the all-time great items: cheap, light, stuffs into a pocket, and really makes a difference in your warmth and comfort.
A sitting cushion is always a great item to strap to your hunting pack. Not only will it keep your butt off of wet and cold mud, grass, or metal stand seats, but it also is just more comfortable to sit on for hours than a log, the ground, a rock, etc. Go luxurious on this item: get a really thick foam cushion!
One item I highly recommend is a powerful headlamp. This lets you see in the dark with both hands free. Make sure the batteries are good before you go into the woods.
Some other items that are not necessary, but that might make your day more pleasant or your hunt more successful:
- pop-up style ground blind
- shooting sticks
- latex gloves and wet naps
- antlers or rattle bag
- grunt call
- small knife for skinning
- bone saw or heavy knife for splitting rib cage and pelvis
- small binoculars
- rangefinder
- wind puffer bottle
- deer sled