How to Do It What are we doing here? Photo illustration by Slate. Photo by Getty Images Plus. How to Do It is Slate’s sex advice column.  Have a question?  Send it to Stoya and Rich here.  It’s anonymous! Dear How to Do It, I’m an 18-year-old woman in college. I never dated in high school, but I feel like I’m more ready for relationships and sex now than I was before. There’s this guy, a junior on campus, “Luca,” that I really like. We’ve bumped into each other at a few events, and he’s really nice. But I don’t know how to deal with the interactions we’ve had—specifically, what happened at a recent party. He is interested in some of our shared academic interests, so most conversations start about marine biology. We flirt. Mostly, I initiate flirting, he ignores a pass or three, and then comes around and flirts back just as I figure he’s not actually into me and think about ending the conversation. But then, once in a while, he seems to react intensely.…