If you are serious...most folks start preparing for a hunt of this nature literally years in advance...
A well sighted in rifle, as previously mentioned, would be first, with quality glass on it, and appropriate ammo. A guide might be able to help you with this, if you dont have one. Start talking to him now, not in a week or two! Will you need a sleeping bag?
Next, what are the extremes of weather you are going to run into? A down sweater is a good idea, they pack very small. Most likely a couple pairs of synthetic long underwear (NEVER COTTON!). A pair of waterproof boots appropriate for the climate...well broken in, without exception, with several pairs of appropriatly fitting cold weather socks (NEVER COTTON). A quality goretex rain suit, top, bottom and hat, which you will probably live in. A good quality bug suit, probably a Thermocell bug repeller with refills. A good qualiity day pack with your essentials, (canteen, first aid kit, snacks, firestarter matereials, spare ammo, etc.) A good quality knife. Spare eyeglasses and medications, if you need them. A very good quality solid walled gun case.
In your pockets: quality folding knife, dependable lighter and firestarter, and a good quality compass. GPS goes in your bag if you have one, but the compass and knowing how to use it is more fail safe. Many details for clothing, but your guide is your best recourse. of course, you have your list of outfitter references you contacted also, who can fill you in.
Do you have your hunter safety class done? Most states and Canadian provinces require proof of one.