Hey Kevin, the most important part is over - admitting you are an elk hunter (or will be one - welcome to the addiction!). Granby has a lot of great hunting but in my opinion, save the money on the trespass fee...there are thousands if not millions of National Forest acres here and you're welcome to hunt them. In my experience most of the elk are still on the forest because they haven't been pressured on to private land yet - that doesn't start until muzzleloader season but then its fairly subtle. Now when the rifle seasons start up, the elk hit the private land.
The other guys are right - get in shape and stay that way. If you can get to Denver a day or so early it will at least start to acclimate you, we're at 5,000 feet here so take it slow. If you can get to the mountains a day early that is even better. Drink lots of water - hydration is key to combating altitude sickness which is no fun - I have experienced it. Also take it easy on the alcohol and coffee.
Being a good caller is essential but trust me when I say learn your cow calls and be able to bugle. I think bulls get bugled to so much that they become wary - you can't go wrong with a cow call. Think of it this way, if a bull has his girls with him and a big bad bull is bugling and wanting to fight...the smart thing is to take the girls and leave. If a bull is bugling bugle back but sound inferior otherwise you may scare him away. Cow calling is key. I use a lot of Wayne Carlton's calls - estrus whine, mac daddy, fightin cow, lonesome cow - I am partial to these calls because they are simple and work
HS Calls. I have heard from a lot of people that the hoochie mama is a good call but I don't like the hand calls - personal preference.
Get a good pack and make sure it fits. Also make sure you bring a variety of clothing because the weather can change in a heartbeat. I hunted last archery season in warm weather and snow...be ready. Another great source is Jay Houston's website
Elk Camp and his books Elk Hunting 101, 201 and 301 are awesome.
Other questions just let me know. I am NOT an expert but I hunt elk with a bow and absolutely love it!