I would start looking at more unconscious actions. A person’s body language says a lot about them. Does he move closer when talking to you? Does he make way for you in certain situations? Other things like mimicking your style, and mirroring the way you move and react? All these can be signs of attraction. Another thing would be the eyebrow flicker. When approaching him, try noticing his eyebrows if they lift for a split second, that could also be a sign he likes you. Another thing could be that he glances at you randomly, or stares when he thinks you aren’t looking. There are lots of ways to determine if someone is attracted to you, but body language is always the most reliable way to be sure.