Honestly, I don't flirt at all in a traditional sense. I don't chat people up, I just talk to them and see if our personalities spark.
There's certain stock conversations that I run to see if someone is the kind of person I would be interested in. If they can get through to the end of about ten minutes of conversation, enjoying my sense of humour and being interesting back, then tbh I'm about done. I'll just be charming a while longer and then take their knickers off in my own good time.
Lead with a compliment, find out more about them, take an interest in whatever they talk about(that's a learned skill btw... show a little knowledge, but let them teach you too... it makes people trust you and makes them feel smart... it gets them talking comfortably and feeling good about themselves), make clever jokes about things. If you do it right, they'll tell you anything in their life and feel like they've known you forever very quickly. From there, if I genuinely like them, then I'm set. Arrange to see them again or sex them up a couple of hours later, depending on the vibe I get from them. Some people like to jump right in, some people like to connect more, either way is fine.
It sounds kinda arrogant, but I promise its not meant to sound like that. I can definitely NOT sleep with anyone. But if they are the kind of person I like (clever, funny, under-appreciated which is normally bundled with some self-esteem/daddy issues) then they are likely to be the kind of person that would sleep with me (clever, funny, hard to please, slightly domineering male).
Its all about choosing the right people to talk to. If you are compatible, you won't 'flirt' at all, just sit and enjoy talking. I think thats what most people forget not just with flirting but with meeting people in general. They only go after impossible gorgeous air-headed attention whores and are then complain they never manage to talk them into bed.
Now sure you have to see some kind of sexy in someone to wanna sex them up, but tbh almost everyone has that in them and it becomes a lot clearer when you talk to them. Personally I think everyone is pretty when they smile, and it doesn't matter about size or lack of it. If you see someone who you think just has a something that gets your attention, go tell them you think so. Make them smile and talk to them and see whats to do. Being open minded to anyone means you'll be a whole lot happier IMHO, you look at the world differently.