As far as seasonings are concerned, at least, chicken skin is not the permeable membrane you'd expect it to be. Spices simply can't get through it. But put the rub or marinade under the skin and the meat will soak up the flavorings like a sponge. And the skin seals in the juices. Here's how to do it.
1. Gently loosen the skin from the body of the bird. To do so, start at the neck and tunnel your fingers, then your whole hand, under the skin to separate it from the breast meat. Slide your hand in deeper to loosen the skin over the thighs, drumsticks, and back. Work carefully so as not to tear the skin. This may feel a little weird at first, but it gets easier with practice.
2. Spread the rub or marinade under the skin with your fingers or a spoon. Place the bird on a platter or in a roasting pan, cover, and let marinate, in the refrigerator, for several hours or as long as the recipe instructs.
3. Use the same technique to flavor halved or quartered birds as well as whole breasts.