Perhaps we should define our terms here. It's quite easy for someone to give a delicate compliment (as s/he sees it), which feels to its recipient like verbal rape. A week or so ago I heard a woman complaining about a trog who saw her cycling by and leered "I'd like to be the saddle on that bike".
I would gently suggest to those proposing flirting techniques that using the appearance of the body God gave a woman as a reason for admiration is less loveable than admiring her for skills she has developed.
If the same man had told the woman she was a wonderful cyclist, he might have got somewhere. (Though somehow I suspect that the leering tone of the comment meant he didn't want to get anywhere - he wanted to make her feel threatened and inferior.)
I'm pretty lousy at flirting myself - too shy - but I'd suggest that the best way to flirt is appreciation, smiles, genuine kindness.