Go to the Colorado Department of Wildlife web page and do some investigation. You will definitely want to look over the hunting regulations. You can and should order a copy of the "Colorado Big Game CD" that you can locate at this web site. This CD provides a wealth of information on harvest success on a unit-by-unit/season-by-season basis. The CD also provides information on drawing probabilities, which will also be important for you to understand. Some units you can expect to draw a permit on your first try; other units you may need to try 10 years before you draw. One thought to consider is doing a cow elk hunt on your first trip: cow elk are easier to hunt, the license cost is about 1/2 that of a bull license, and cow elk meat is probably better tasting than bull elk meat. Additionally, you might be able to get away with using your .25-06 on a cow hunt (use heavy bullets of tough construction, for example nosler partition), but the others are right to steer you away from using the .25-06 for bull elk. These are very big animals -- about three times larger than deer, on average. Colorado has the highest probability of drawing for non-residents.
Elk are located at different places at different times of the year. In warm weather elk like to be up high in cooler country, just at timberline when possible. Being up high keeps them cool and also reduces the pesky insects that plague elk. So, if you are going to hunt an early season such as archery, muzzleloader, or first rifle season you will want to consider hunting high country. This means you probably don't want an early season license in a unit which has only low country because the elk might not be there but rather miles away, outside your unit, in high country. Similarly, if you are looking at a late season hunt the snows will push the elk down out of the high country: don't plan to hunt the wilderness area in the national forest public land in mid-November. Probably by then the elk will be pushed down to lower elevations, maybe on private land that you won't be allowed to hunt unless you shell out thousands of dollars. Consult locals on what to expect in a given unit. If you can't contact locals through this or other hunting forums, call a field office of the Colorado Department of Wildlife and talk to a field biologist. Some general places to consider are the Flat Tops area, the West Elk Wilderness area, and the San Juan national forest area. I suggest you get a Colorado Gazetteer which contains moderately detailed maps of the whole state. When you have decided on a Game Management Unit (GMU) you will want to get more detailed maps, including 7.5 minute USGS topographic quadrangle maps of your specific planned hunting area. These maps will provide detailed terrain information which are very helpful in planning your hunt and hiking plans.
You should try to get out to your selected hunting unit for a couple of days of scouting in the summer before your hunt. You will want to know how to drive to your hunting area. You will want to know what the lay of the land is. You will want to identify several good camping spots, bearing in mind that others may get there before you for the elk season and already have taken one or more of your preferred camping spots. You will want to identify good places to glass from to start your hunt. Try to imagine how other hunters may hunt this area and plan to position yourself so the elk may tend to be driven to you. If you don't do this during the summer, you are likely going to wind up doing this as part of your hunt. Personally, I would rather have this kind of business handled in advance so I can focus on hunting during the hunting season. Also, try to arrive at your hunting area a couple of days before the season to get set up and do some pre-season scouting. Wouldn't it be nice to locate elk before opening morning, go to the known position of the elk on opening morning, and take your elk immediately, before they get spooked and stirred up by all the other hunters?
Be in excellent condition. Being young has its advantages, but you will also need to condition yourselves through strenuous physical exercise. Begin this process at least 4 months before your hunt, preferably 6 months before your hunt. If you are overweight, lose the weight. If you undertake a strenuous exercise program, which I suggest that you do, increase your intensity level over time, don't subject your body to sudden large increases in exercise intensity. You can't achieve your end goal overnight and if you try to you WILL injure yourself and delay reaching your goal. When exercising intensely, pay attention to eating sufficient protein. Eggs, milk, meat, fish offer good sources of protein. Protein supplements in the form of Whey powders can augment other sources of protein. You want to focus your conditioning effort on aerobic exercise, which will help you adopt more readily to the high altitude, but strength training your upper body will help with handling the meat. I condition on 6 days and rest the following 2 days. On days 1, 3, and 5 I run 4.5 miles at 5.5 MPH, half of the distance with a 6 degree slope dialed into the treadmill. On days 2, 4, and 6 I do strength training including two sets of push-ups, two sets of sit-ups, two sets of arm curls with 25 LBS dumbbells, two sets of leg squats holding a 25 LBS dumbbell in each hand, lunges, and various other leg and arm exercises. On strength training days I run 2 miles at 6 MPH with no slope. This has put me into just about the right kind of condition, I think, for my backpacking elk hunt I will do beginning in three weeks. Remember, you want to be able to keep on hunting for at least 5 days, covering a lot of ground at high elevations. Endurance and stamina are the key physical attributes, not short-term maximum strength.
Try to hunt well away from the roads. It is said that 90% of hunters stay within 1 mile of roads. To me that means get in more than 1 mile before beginning to hunt, in order to avoid crowds. If you go into the woods, be sure to carry appropriate equipment including (1) map & compass (even if you have a GPS, have the magnetic compass and 7.5 minute USGS topographic map for your hunting area on hand -- electronics fail and batteries expire), (2) matches in a waterproof container, (3) fire starter material, (4) an emergency thermal blanket of some sort with which you can try to retain some warmth if you get stuck out overnight, (5) a knife, (6) extra food, (7) a flashlight with extra batteries, (
some sort of first aid kit, (9) drinking water, (10) toilet paper, and (11) appropriate extra clothes in case it gets colder or begins raining.