How can you tell if a guy likes you?

Frequent flirting
frequent texting/phone calls/emails
asking you about your love life
hanging out with you all the time
touching you whenever he can
teasing/play fighting

But by far, the best way to tell if someone likes you is to step into their personal space. Get awkwardly close to him and see if he backs away. If he doesn't, that's the biggest sign of all.