The Gold Standard
Black diamond pretty much owns the skin market for skis. G3 also makes quality skins but I've heard from people who've had both that the Black diamond ones are a bit more durable. The adhesive works even if it gets a wet and the grip even on steep slopes is impressive. If you're going to do any steep climbing, go with the ascension over the mohair because it grips better on steeper slopes. I recommend getting a skin that is at about as wide as the ski is underfoot. Obviously the tip and tail of the ski will be wider and the skin won't cover it completely, but if it's at least as wide as the center of the ski it should be able to climb with minimum slippage.