Observe his body language when he walks into a room. According to the Learn Body Language website, if he enters slowly, with a sure stride and erect, confident posture, he is marking his territory and making it clear that you are included in this.
On the other hand, if he enters nervously and appears unsure of himself, this signals that he likes you but is fearful of rejection.
Observe how he sits when he is next to you. Does he maintain his confident poise, appearing relaxed and at ease? This suggests that he is comfortable with you, and also that he is confident that something will happen between you.
Notice how he takes up the space around you. Is he an alpha male, sitting protectively close to you so that no other men can interfere? If he places his keys, cigarettes or phone alongside your handbag, it signifies that he is sharing his territory with yours and imagining you both together.
Look into his eyes. If he holds eye contact and smiles with his eyes as well as his mouth, he is keen to connect with you.
Notice how much preening he does while he is with you. He may ruffle or smooth his hair, depending on what cues he picks up from you as to whether you prefer a polished or a roughed-up male. According to Learn Body Language, he may fix his clothing, or place his hands on his hips to draw attention to his genital area. These are responses to unconscious messages he receives from you about the kind of male you prefer.
Watch how he behaves towards you after he leans a little closer into your personal space. If he smooths your hair or leans forward to whisper into your ear, he is testing your reaction to him getting physically closer to you. If he still seems confident, he is sure that you like him. If he seems more nervous than previously, he needs a little encouragement from you that you appreciate his efforts.