How to flirt?

Throwaway for embarrassment's sake. 24/F

I was raised in a very success-minded home, I have three siblings with doctorates from ivy league schools. Our family is one that neither hated nor loved, and we considered gesture and politeness to be higher than physical or verbal affirmation. I have never been in an fight with a single family member, verbal or otherwise, and I've actually never heard my parents raise their voices to each other (at least in front of me). I've never said "I love you" to my siblings, and even when I end a phone conversation with my parents, they rarely tell me they love me. We also don't really hug, or do any sort of physical affirmation of love. In fact, when my extended family gets together for holidays, we handshake when we see each other. In lieu of that, I can say with great confidence that both my parents and my siblings deeply care for me and each other, it is just not ever expressed in that way.

So I, in a similar manner, have always had problems flirting. I literally don't know how to flirt or even touch other people. I am incredibly confident and independent, but have that sort of "brick wall" type of persona. I have been in no relationships, and have dated sporadically. ALL of my siblings are ostensibly the same way. I have had many, many, instances in my life where a guy friend that I actually liked (and thought I was obvious about it) would tell me way down the road, and generally when it's too late, that he has always some profound respect for me and wished something more had happened.

Thus my first problem with even trying to attract a member of the opposite sex is actually seeming like I'm interested. I can make great conversation, small talk, etc. But most guys assume I'm not even remotely interested because I lack that certain feminine quality to show sexual interest. It's truly difficult for me, because most of my female friends usually reply that it's a "natural" thing they do, while I have to put forth a great amount of effort to even recognize that I'm not being affirmative.

A few years ago I had some resolve to change things with my family, and with my friends, but it's surprising to see how slow the process is. I'm trying to call my siblings just to talk, write cards, say those three words to both family and best friends. I think it is working... sort of.

But physical affirmation is the absolute hardest. Hugging is nearly impossible for me. Has anyone else had this problem, if so how did you get over it? What are subtle ways I could change? What are simple ways I can show interest in a guy without being over the top (or looking like it was contrived)?

Edit: I was curious how affirming your family is toward each other?