In my experience, and I'm an admitted old lady now compared to you, Ian, one ever read me or my girlfriends as timid. When we found someone we were interested in, we'd let him know. But that's something that'd be more likely to be in private in how we'd respond on a date than something others would pick up on. Typically you play it cool the first few dates till you make sure you like him and he's interested in you, and then if you like him, you respond to his advances and keep going out with him and/or, in time, initiating plans to do further dating/together.

I know y'all don't do quite as much dating and do a lot more straight-to-the-hookup thing nowadays. If you could do more courting of the girls and they wouldn't put out so easily, I think the relationships would benefit.

We show guys we're interested in how we respond to their kiss and their touch. In how we flirt. In whether or not we say yes to dates and other things. In what we say in emails and IMs. At least if we're not game-players that's how we show 'em--the direct way. But smart girls won't be blatant about showing it real early in the acquaintance.