I am not an expert, I fell in love twice, and married the second girl I ever fell in love with (Or maybe the only one Io have really loved and love now).
However, I think that eye contact is important. You should never stare at a lady, usually a pussy eager looking man is not appreciated. Try to look at them in admiration, manly, virile, self sure, but never cocky or arrogant. You should lead the flirt, as a man, but she should not notice, she has o have the apparent lead of it: since the night of the times, ladies choose!
Delete sex from your mind: every time you try to seduce a woman, you are seducing a Queen and a Lady, not a whore. Make her feel special and important. Be elegant surprise her with a smart personality, and an open and charming heart. Don't be a clown, a true and sincere heart is your better business card.
She has to be on cenntral stage, better, on the only stage. If you flirt with a woman she has to be the only one in the room. You can't flirt with two ladies in the same room, or flirt and in the mean time mess with your friends.
Here comes the most difficult part: being flirtatious and dedicated to her, without giving the impression do be desperately looking for a woman and, worse, a weak personality. Remember tat men, as well as woman, have to preserve their dignity. A man should be a companion for his woman, and the shelter from any danger. Therefore he has to be strong but kind, and to give the idea of reliability.
Keep your hands off, if not allowed to, and keep your eyes up: she speaks with her eyes, not with her breasts or ass.
Try to have a relaxed and kind smile, don't laugh as a clown or be nervous. And the voice, very important. Deep, virile, but sweet as honey.
Women are complicated, but isn't this the reason we love them, or, better, te reason why ne of them stored in our hearts and stayed ther forever?
MOST IMPORTANT LINE: BE YOURSELF, OR YOUR FLIRT WILL BE LIKE A BUBBLE, EVANESCET AS SOON AS SHE WILL UNDERSTAND SHE HAS TO DO WITH A BOY WHO IS PLAYING A PART, AND NOT WITH A MAN.