Just throwing some random thoughts out.........
Make sure your boots are comfortable, your pack fits (and can accommodate all the gear you choose to carry), and your sleeping system is good for the conditions you will encounter and your own sleeping style.
I can't do hammocks, 'cuz I tend to roll around and sprawl when I sleep. I do like the Thermarest prolite (3/4 length with my empty pack under my feet/legs), but I've started using a 3/4 Ridgerest along with it, 'cuz the ground seems to keep gettin' harder and harder as I get
older. I've shifted to using tarps if the weather forecast is good, or the bugs aren't bad, but I'll use a tent (Big Agnes Seedhouse SL) in the shoulder seasons.
Get some work-outs (ie walking hard on hills w/ a pack) in before ya go bustin' into the full-on alpine, and start with some short trips to get your gear (and body) wired.
On your first few trips, you'll probably carry too many clothes, too much food, and too much gear. Learn what you really need, and trim the weight on subsequent trips. A light pack is safer, will let you travel more miles, and is ultimately much more satisfying. Try to remember that for hundreds of thousands of years, we got by without all the doo-dads we think we need, and survived just fine, walkin' naked in the world. Just like the elk, bear, wolves, and other critters do today.
Go minimal, and embrace discomfort. The worst thing you can do is to expect your going to be as comfortable in the woods as you are in front of your living room big-screen. It's different worlds. You can take a solar shower bag, and a full set of cookware, soap, shampoo, book, lantern and flashlight, tent, extra clothes, etc, but the weight's gonna hold you back, if it don't kill ya. It's all about what ya
need.
First aid? Best advice I ever got was in a WFR class I took 15 years ago. "A big bandana, 30 feet of duct tape, and a few ibuprofen." Add specific items as needed (epi-pen for sting allergies, personal medication, etc), but the trick is to be careful, and avoid needing a full-on SAM splint, cold compress, or multiple types of bandaids. Most "wilderness" first-aid rigs are total overkill, and useless weight.
GPS? Unneccesary except for glacier travel, long wilderness river floats, extensive off-trail travel, or if you're a dumb ass when it comes to on-trail navigation, in which case, it probably won't help anyway. Save your money for a good sleeping bag and/or boots. Learn to use (and love) a map and compass.
I like lightweight capilene base layers (yeah, Patagucci still makes 'em, and I really don't care if I reek after I've been tramping for a few days. Jesus, it's not like I'm expecting a job interview..) along with wool mid-layers, and cheap (ie non-goretex), light-weight rainshells for clothes. Hit your local thrift stores, and look for a pair of women's stretch-wool (90% wool/10% spandex or nylon) pants, or a loose-fitting pair of lightweight wool men's dress pants, and a cheap wool shirt. Wool is the ticket for sitting around a campfire, 'cuz sparks burn right through that synthetic stuff. A lot of high-end outdoor-gear companies (Ibex, Patagonia, Cloudveil) are bringing wool back into the line-up, and it's about time! (even if the high-end stuff is, umm, high-end) Wool is good stuff. My favorite backpacking shirt is an old Pendleton I bought for $2 about 20 years ago. I patched up the torn elbow, and the thing had instant trail cred, which it's lived up to, to this day.....
I would (respectfully) disagree with previous posts about freeze-dried food. Some of it is actually pretty good, and that stuff is light. I especially like "Enertia" Mac/cheese, Spaghetti, and Goulash. Campmor sells it on-line, and here's the manu's site:
http://trailfoods.com/
Most of all, don't get caught up in "gear hype". It's nice to have all the info on the 'net and everything, and titanium french presses/800-fill-weight down bags make me drool, but ultimately, it's about gettin' out there. Throw some stuff in yer pack, and go do a couple of quick overnights. You'll figure it out, and anything you miss is unlikely to kill ya. Might even make ya stronger and/or wiser. Ya never know.........
It ain't the gear (or lack thereof) that's gonna hold ya back. It's yer own head, and where it's at.
Get on it, and remember to have fun.