I've found that when 'flirting with magic' it's good to make use of the 'leave them wanting more' rule.
Always leave at a point that your spectator's have seen an awesome trick or 2 leaving them curious to see more and they will look you up or come see you later for more.
Do an awesome trick, something quick and visual - not too involved and then leave them with a very 'james bond' smile and look them in the eyes as you go to walk away.
Just do something that your comfortable that you can perform really well, or something that just works.
I like to do stigmata if it's bright as it's powerful, mind boggling and breaks the 'touch barrier' as you get them to hold your arm - great ice breaker.
If it's in a darker situation, I'll do my coin bend (will be out soon. search my name and the word 'Altered' in you tube.) as again it breaks the touch barrier and leaves them with something to remember you by.
You should try leaving your number, unless it's someone you see around the place alot - then I feel it's more impactful not too - next time they see you, or if they've seen you in a certain place alot, they'll find you.
I should write a book on this stuff! It's already been done however, any one that's picked up 'Flirting with magic' reviews please!
Hope that's helped!
D.