It must be durable, comfortable to operate in, and layered for adaptability. Polypropylene or similar material makes a good first layer for wicking away perspiration. Often this layer is adequate during active search operations. An insulating layer of wool, or synthetic pile or bunting offers warmth even when wet. The outer shell must be wind and water resistant.
Breathable fabrics are effective, but expensive.
Whatever is worn must be able to withstand the abuse found in the underbrush and rocks common to this area. Your feet, being the basic means of transportation, deserve considerable attention. Sturdy hiking boots are necessary, as are a couple of layers of socks - including wool. An extra pair of dry socks in your pack may have a dramatic impact on your attitude in wet and cold conditions. Moleskin should be carried by everyone, and applied at the first signs of 'hot spots' which lead to blistering.