I think directly or indirectly compliment a woman's physical feature the first time you meet her is abrupt. It can make her think "Meh it's just another guy who wants to hit on me."
I don't like to say that "hitting on" has a negative connotation, but I really think many woman thinks hitting on has some degree of superficiality, like your ultimate goal is to get her attention for your own enjoyment, not to really acknowledge her (I agree that people have truly good intentions in compliment in most cases though.)
Compliments are great, but it may be more compelling to say something qualitative on the inner side such as "Good work!" than something that only reflects on the outside, such as "Woah, I bet you're a professional model."
I think things like "Hey, did you invite all these people? I thought it was just going to be the two of us." is witty
It's flirty but doesn't lose friendliness at the same time.
Of course, above comments do not represent all women on earth.