Look into his eyes. If he looks back and makes eye contact, there's a pretty good chance that he might be interested. This is also a really good flirting technique. Holding his gaze, especially if the two of you are talking, will create a connection between you two pretty quickly.[1]
• If every time you look up, he's looking at you, that's also a good sign. It means that he likes looking at you, but he might be too shy to make his interest known or to approach you!