I may not be a posse member, but I too went on my first caribou hunt a couple of years ago. As far as hints go, good (and by good I mean dry and warm) footwear, rain gear(even for days it's not raining to help cut the wind), comfortable binocs(you are going to use them all day every day), and laser range finder. The landscape is totally different than anything I'd hunted in before and distance it tough to gauge.
I personally think bringing a backup to your bow is important. They are wild game and not everything is like a hunting video. There may be days where you can't seem to buy a caribou. And when you do there may be a trophy of a lifetime that is traveling parallel to you at 200 yds and you have no opportunity with your bow. Where we were, it wasn't impossible with a bow but the rain and snow fell sideways every day. I think the wind slowed to about 30 miles per hour one day. But, like the bou it never stopped and only temporarily slowed down in it's travels. Bring a camera and just enjoy! You will be hooked for a lifetime.