its eye contact that does it...
for definate.
that look... she knows, he knows.... seed is planted.
If you are naturally funny and humour comes easily... it will work for you.
If you are not, even if you are shy... if she likes you, and there is flirtation, it will work, you do not have to be the most confidant, nor the most handsome.. there just has to be something about you.
I guess the location makes a difference too as to the approach you make..
I am now married and thirty five and I donot do clubs as it doesnt interest me.
However, I have found that even if just having a meal with girlfriends in a pub or restaurant etc, that eye contact still happens.
They look, you look, they look back, catch you looking back.... they smile... you smile..and so on..
and you just....know.
That does not mean you have to do anything about it.
But if I was single again, I would much prefer that lingering sort of initial eye contact ..smiles.. flirty courtship than a finger ran over my bottom!!!!!