Is there any advice for fatherless young women, how to flirt and date?

My main trouble is that I have a lot of trouble expressing even subtly that I am interested in someone romantically or ually. With a stranger I currently find attractive, I find it very difficult to flirt with him even in a basic way, despite the fact that he has tried to flirt with me a lot. I keep urging myself to try, to put myself out there, but always there is this seriousness, or heaviness, that holds me back. Please, what can I do? I feel as though that whole world is so unknown, it is overwhelming.