READ! The internet, books and magazines were what got me rolling.
I did the same thing - first gun at 21, went on my first hunt at 22, by myself. Online, I read here, TFL, US Hunting Forums and did a heck of a lot of Googling. Subscribed to Field & Stream. Grabbed some books, F&S's "Complete Hunter" is very basic but it's not a bad starting point. Bought some DVDs, they were particularly helpful in learning how to set up and call turkey. I took a hunter's safety class in Illinois, as well as a Wisconsin DNR-sponsored first-time deer hunters' class. While, by the time I got to these courses, they did little for me, it was good reinforcement of what I already knew.
There's a lot to it, but you should pick it up quickly. Know your stuff, and practice, practice, practice. The adrenaline surge when it's time to pull the trigger is staggering, and you will have a heck of a time holding your target. That's inevitable. What's not inevitable is becoming skillful with your weapon. My "good enough" is (sadly) a truly amazing shot for a lot of guys who have been hunting longer then me (my "good enough" translates to two heart shots and a double-lunger close to the heart on three deer taken between 150 and 225 yards - turkey and pheasant aren't quite so precise). That said, my "good enough" is an embarassment to some of the real marksmen I know. The point is you have to be sure of yourself under good conditions, so once you're in the hot seat you don't have any uncertainty of what's going to happen if you can do your part. If you have any doubt, if your gun took a funny bump while you were cleaning it, if you bought a new box of factory ammo and it looks even a hair different than the box you sighted in with... get back out to the range. Have all your wrinkles ironed out, because lots of new ones are going to pop up once you step outside with your gear in the twilight.
Speaking of which, scout. I don't do enough of this, but I wish I had more time to. Nothing puts a damper on hunting like not seeing anything in spite of the cold and misery you endure. My first turkey season, I barely saw anything, and I'm sure it would have been nothing had I not gotten out and scouted at least once. Even if you don't know where the animals are travelling, you've got to know the terrain before you're stumbling around in it before first light. It will also help you know what you're going to want in the field. How many layers will you need? How much water do you drink? What about snacks? Cell phone, radio, GPS - which I would recommend, I was only a half mile from my car, versus the two miles away I'd been the day before, when I bagged a turkey this year and still managed to get a little turned around - and so on and so forth.
So yes, read, and ask all your questions. There's lots of us adult newbies, and we all think we sound like dopes, but the reality is the hunting community is one of the friendliest I've been privy to, and people are happy to help. The later degrees of preparation I mentioned, not everyone takes. Particularly hunting families where they have routines. But when you're going in alone sometimes, I can't tell you how much it helps to be able to anticipate how things are going to happen by having practiced and planned most aspects of your hunt before anything's in the crosshairs.
Addressing one of your specific concerns, once you do harvest an animal, field dressing is usually just a matter of taking what's inside, out. This will vary from animal to animal, and it's just as easy to get info on as any other aspect. Preparation for eating's the same way. A lot of people get larger animals processed and handle their own birds and small game, but it's up to you. If you plan to get anything mounted, make sure to learn where to cut so you don't screw up the taxidermist's ability to do up your animal - some people that "overdress" their harvests preclude taxidermy with their obliteration of a cape, hide or area of feathers.
Anyway... dig in and when something doesn't make sense, just ask and you'll get good answers. Best of luck!
You need all the stamps and hunting license to duck hunt (state and federal waterfowl stamp) and gear to stay warm and dry, and, of course, a good 12 gauge to shoot steel shot out of.
