First thing that comes to mind is, How are your boots??? Waterproof,insulated and comfortable???
I don't know how your friends hunt. But alot of hiking is usually involved. I buy at least a 1/2 size bigger to accommodate for heavy socks. I also use feet warmers in the mornings.Nothing makes a person want to go back to camp more than cold ft.
If you're looking for clothing.....Wool is best. I buy mine at an army surplus store for a fraction of what some fancy name brand stuff will cost. Pants with anle buckels,sweaters heavy and lite.Good wicking underwear is a MUST also.

I could also suggest a filtering water bottle.Fill it up at camp in the morning so that the filter does not freeze up and then you usually have a water source for the rest of the day. If you can find water that is.