Any erogenous zone ... and no, I don't mean genital zone (well, that, too)
Anywhere the skin is thinnest - wrists, inner arms, back of knees, inner thighs, temples, behind the ears, groin area where the leg joins the body, lower back ... anywhere the skin is thinnest, that's where the nerve endings are right there -
Licks, nibbles, light touch (fingernails work great) ...