I like the way rdos thinks.
In my humble opinion, the definition of flirting is simply to verbally or non-verbally express your physical or emotional attraction to another person.
And there are no 'rules' of flirting - anyone can flirt, so long as it is attempting to make the other person aware of how you feel/what you want.
And also, everyone flirts differently as well. My way is usually a very subtle and sneaky way - usually the female has no idea, but people who are observing might question if I am or not. With my ex-girlfriend it was more playful and hidden (e.g. her friends asked her who she liked and she didn't answer, then they left us alone, and I asked my ex in a playful way 'Yeah, X, who DO you like?
" and another time her friend asked her if she had a boyfriend, she said yes but didn't reveal my name due to us having the relationship private, and I went up and said "Yeah X, who's your BOYFRIEND?
")
I'd say even if you're an aspie and too shy to talk to a girl, but instead become the sweaty, nervous, shaky guy, that's still 'flirting' in a sense, because it expresses your feelings. Some women even like that kind of stuff and find it 'cute', so if she likes you back then yeah it's not a bad thing.
OP gave a good example of what I mean. A nervous girl even just shyly saying 'hi' is 'flirting' (by definition and by personal opinion).
So yeah, I'm good at flirting, my own ways, my own methods, so long as all 'rules' for flirting are broken and instead only defined as 'expressing your attraction to another person'.