Separate influence from control
Presentation, communication, familiarity and context can affect how people perceive one another, but attraction is not a guaranteed response you can trigger on command.
Look for reciprocity
Instead of trying to decode one gesture, notice whether interest is sustained across the interaction: conversation continues voluntarily, questions go both ways, and future contact is welcomed.
Body-language cues are ambiguous. Treat them as context, not proof of attraction or consent.