Flirting and Other Fine Arts - Part 1

I used to think I didn't know how to flirt (not that I'd say I'm an expert now) but I had an "A-Ha!" moment a few years ago:

I was at my hometown bar with friends and I was chatting with The Hot Bartender.  We were friendly and would chat whenever I came in.  I walked back to my friends and one said, "Wow, you were doing really well with him!  He's totally flirting with you!" and I was like, "What???  We were just talking!!"  That was when I realized, flirting is really just talking.  I'd thought I needed a line or a move, but flirting is just... talking.  With intention.  And a casual arm touch doesn't hurt.  

I've been thinking a lot about flirting lately.  What makes flirting flirting?  I've been working on set and in the film industry a lot of people flirt but it doesn't really mean anything.  I call it Work Flirting, like working in the service industry, you have to interact with a lot of people and it's a fuzzy line between being friendly and flirty.  One guy freely admitted that it was just a way to pass the time and if I called his bluff he would back down.  Honestly, Work Flirting that I know is Work Flirting is fine by me, it can be a fun break in long stressful days.

But how do you tell if someone is Work Flirting or Real Flirting?  Unfortunately, it's easier for me to Work Flirt (with guys I'm not actually interested in) than Real Flirt (with guys I'm actually interested in).  There was a guy on this job my friends started calling my Boyfriend, who I actually genuinely like, and I would get SO NERVOUS talking to him.  It felt like being a teenager again, we would find any stupid reason to talk to each other (we had basically no work reason to talk) and while we're talking in my head I'd be shouting at myself "SAY SOMETHING INTERESTING!!" but sometimes we'd just stand there smiling at each other like idiots.

Why are there some guys that I can't help but flirt with (either Work Flirting or Real Flirting) and other guys that I'm so nervous around that I'm nearly incapacitated?  I couldn't be friends with Sugar Ray Guy and B#9 was because we kept flirting with each other, even when we were trying to just be friends.  With both of them I found conversation pretty easy from the beginning, but there was alcohol involved and that can definitely help.  There was also more pressure at work, I only had a few instances each day to talk to him (our paths didn't cross often) whereas with SRG or B#9 we were hanging out one-on-one.  If I got to know Boyfriend (sorry/not sorry, the nickname stuck) better, would I be less nervous around him?

(Continued in Part 2)