Betty Boop was sexy, Blondie was sexy. Neither of them exactly had high tech skin. Sexy comes from a lot of elements, the character, the setting, the situation. The classic pin-ups usually featured an element of surprise, an embarassing moment, a cheeky pose, the expression, a few key props … IMO, you should work on those things first and worry about the physics of skin later. Do you want to be an artist or a dermatologist?

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken