The layering principle is key. Woolen undergarments are definitely preferable. Having different thicknesses of base layers allows you to accommodate different conditions. Remember that you should start out feeling a little cold. Boots are one thing you cannot afford to skimp on. They need to be sturdy, with a non-slip tread and stiff enough at the ankle to reduce the risk of a sprain. You should also break them in well, before taking to the mountains. Taking extra clothing with you is highly recommended – an additional base layer and a compressible insulating jacket, for example. It is good to have a change of clothes if you get hot, or simply to relax in over lunch. Your rucksack should also contain a hat and gloves for when the weather changes.
Rucksack. A well-designed, properly adjustable rucksack is a must for any outing. The ideal carrying system has a wide hip belt, and broad, but not thick, shoulder straps, which allow you to vary the load points during the day and to shoot without removing the pack. It is very advantageous if the rucksack contains a weapon holster that accommodates both shotguns and rifles with sights. Partly because it means you can use the rucksack for different kinds of hunting, partly because it saves the strain of having one’s gun slung over the shoulder all day. This is clearly worth the little extra cost. The holster also frees up your hands when you are hiking.