The following is not intended to be all encompassing, but rather a basic check list for trip preparation. It will be rare that any one trip would require all of the items on this list. Likewise there will almost always surely be some items unique to your hunt or personal needs that will or should be added.
Best clothing for cold or cool weather is wool or pile/synthetic fleece materials in layers - avoid cotton as it does not provide warmth when wet. Opposite is true for warm weather hunts where cotton and light synthetics aid in cooling. If your trip is with a guide or outfitter, be sure to ask for their suggestions. They know what terrain and weather conditions you should prepare for, and if your hunt/trip involves travel by small aircraft or on horseback, you may be required to limit weight or bulk.
Years of trips in all kinds of conditions have taught us to listen to our guide/outfitter, do what he says as far as gear is concerned, temper his instructions with our own experience and to be prepared. Here's hoping this list helps you do the same. Good Hunting!