Biggest advice is to make sure you and your cousins are as in the best shape possible, or have realistic expectations on where you can get an elk out from. Doesn’t do any good if you shoot one and can’t get it out. Either have a packer ready to call, or stay within an a certain distance from the road/trailhead. A mile in flat land is nothing, but a mile in CO at 10,000 feet is hard enough, along with all of the deadfall and elevation change. Everything will be much bigger and steeper than you’ll be able to see from maps.
If it’s your first western trip, just learn as much as you can and have fun. There are elk, but there’s a reason success rates are 10% and lower.