Rather than deal with some of the more obvious aspects (where, when, how), let's touch on something Alsatian mentioned;
WHAT CAN GO WRONG.
Physical: There is a very real and dangerous condition some people get called Altitude sickness. Read all about it at:
http://en.wikipedia.org/wiki/Altitude_sickness#Signs_and_symptoms
Conditioning: You don't have to be a triathlete to hunt elk. But you will likely have to go up and down ridges to "see what's on the other side" and this can take it out of you. Especially at altitudes over 8000 feet. Archery elk is mostly in September and they are still at higher altitudes. 10,000+!
Company: Don't come out here alone. Three is bettter than two, and onewould beinsane. Even from camp, tell someone or leave a note as to the general area(s) you will be that morning/evening/day. Getting lost is very easy. You will be surrounded by millions of acres of the same exact trees/rocks/slopes or any other kind of reference point. I don't go anywhere without a compass. And before going, I know from my topo
map(s) exactly what direction I am heading out. I'm more old school than to use a GPS. Especially after having to search for a budy of mine who had one and knew how to use it. They don't always work down in deep forested draws or canyons I guess.
Weapon: You say you will be bow hunting. (There is a section here just on archery). Put all your pins on it! Practice and get good out to 60 yards. Practice shooting up hill and down . . . steep! You never want to take a long shot, but if your only opportunity at that 42X30 is at 57 yards, you're gonna take it because you have practiced it and are confident. Bring a range finder so you know exactly what you're shooting. Fixed blade broadhead only. The mechanicals don't penetrate addiquitly to impact a lethal blow. They loose too much enrgy while openning on impact. Remember, you are shooting an animal that is not much smaller than a horse!
Clothing: Much was covered on this. Wool is perfect, but doesn't come in camo patterns to my knowledge. September in the Rockies can bring you 3-4 or more weather changes . . . the same day! Around here, you dress "in layers". You'll be heading out with frost on the windshield, but by 9 - 10
'clock, you may be down to a t-shirt. Especially hiking around the mountains. Then a shower comes through, and by morning . . . 1 1/2 of snow on the ground! Bring comfortable shoes that offer water resistance and some warmth. I don't care if they are your b'ball tennies, if they are comfortable, wear them. The elk won't mind. And your feet will love you.
Gear: In your day/fanny pack: first aid kit. Adequit amount of water. Snacks like granola bars, candy bars, or even a chunk of that steak you didn't eat last night. Matches that are kept dry. I bring a striker also. Good, sharp knives and a small stone. They don't have to be Jim Bowie huge, Ihelpeda guy field dress his elk a few years ago with nothing but his Leatherman's tool. Very sharp knife. But the thick hide and hair will knock the sharp off even the best Buck. Bring some kind of folding saw. It's a big breast plate, and handy when you need to quarter it out. I bring a small sceen of rope. You'll want to tie a leg up when field dressing. Bring your license. I know, it seems obvious, but get caught bringing a chunk of elkout of the woods without it, and you've ruined your whole trip. Game wardens around here can be nasty. Helpfull most of the time, but nasty when they need it. They carry side arms, and can confiscate not only your trophy, but your gun . . . even your truck! Get a roll of bright orange contractors tape. (I think that's what it's called.) Tie strips on trees as you exit the woods so you can go right back to your elk. I also bring one of those "aluminum foil blankets". You may have to stay overnight. (If you get lost . . . stay put!)
G.P.: Be aware that you may be required to have completed a hunter safety coarse and have to prove it. You should go to the Colorado, Wyoming, Montana, Idaho Game & Fish websites and familiarize yourself with the hunting rules and regs. Each state does things differently. It may change your mind. I'd plan on hunting sometime in the middle two weeks of September. The weather's great (usually), the Aspen are turning colors, the elk are twitterpated and bugling their asses off. It's the best time of the year to be in the mountains.
One last personal note. I never have campfires during archery season. It gets in your clothes and makes you smell even more like danger. IMO
Also, the national average of elk success amongst licensed hunters is one every five years. Around here we say; "10% of the hunters get 90% of the elk". If you have to come home with an elk, go for a cow tag your first year.You have a better chance at harvesting, and gets you aquainted with elk hunting for the next time.
"I've got blisters on my fingers". (John Lennon)