I read somewhere that as a general rule, a very masculine guy shouldn't start touching until the girl touches him first
because you will come off as aggressive. But if you're skinny, boyish-looking or tend to look effeminate, you can touch as
soon as possible and girls will not be threatened so much.
One of the fastest ways to get a girl touching you is the use of humor. Girls like hitting a guy (lightly slapping his arm or thigh) when they're laughing. And then you can touch their backs lightly while adding to the joke, or hold their hand for a while or slap their thighs back.