Hmmm...attractiveness (beauty is in the eyes of the beholder). Healthiness is one way to show attractiveness...good body build, broad shoulders, a good set of abs, muscles, a full head of hair, uhhh...looking like a rock star (more slender) or gangstah (rougher)...this is for guys or maybe even gals. It depends on the individual(s) responding. On the female/feminine side, well groomed hair, long lashes, blushing cheeks (even for darker complexions), velvety skin, hour glass figure, long legs, great hips, either slender body or very buxom/voluptuous...this is a show of health too...you know, a person that glows and smells good, wears clothes that compliments their figure.
People tend to stare even though it's not their intention. And according to the style of the artwork, these traits can be incorporated.
That's the easy part. What's going on in the inside is a different story. I LOVE drawing pretty people...if you want to call it that. It's fun!
To some this gal may look like a clown, to others beautiful. That's why it's so important to hear what the characters think.