OMG. MarkWatney, You nailed it.

Austin Ellen, I Love to flirt! Because I can! LOL! Absolutley!

To all above/below mentioned, I would add Humor. Being funny is paramount, imho.
Humor makes me squirm with delight, especially when first contact is initiated. I love jesting with words and flirting with my Future-Ex-Lovers. Flirting, for me, extends my date experience, because it can start weeks before the actual meeting. I/you banter on pm's, get exited, fantasize, run-away with my imagination, prepare, get pretty and get READY. Later, after date is over, delight can provoke even more flirtation. It can go for a long time!
I guess, I am easily exited and aroused by smart and knotty flirtations. And compliments. And gifts. And... And...and...