A warm smile is lovely. It is not a signed declaration of romantic intent, old boy. Look at patterns of interest and whether the connection goes both ways, rather than treating every laugh or glance as proof.
Look for reciprocity, not clues
Does she ask questions back, make time to talk and sometimes initiate contact? Those are more useful than reading meaning into one moment. Friendly people are allowed to be friendly without secretly asking you out.
When you are unsure, be straightforward
If conversation has been easy and mutual, suggest a simple plan without pressure. A relaxed invitation gives both of you clarity. If the answer is hesitant or no, accept it and keep your dignity intact.

METHOD✶
Make it work in real life
Write down three things you actually know about the interaction, then separate them from what you are guessing. That simple distinction can save a remarkable amount of mental drama.
Everyone brings different experiences and expectations to dating. Pay attention to the person rather than relying on a single rule, and don't assume somebody else's interest, availability or intentions. A good outcome is clarity and a respectful conversation, even when romance does not follow.
THE GOLDEN
RULE.
Attraction isn't a switch you can flick in another person. Work on being somebody comfortable, engaging and respectful to spend time with — and give others the freedom to choose for themselves.
YOURS, MONTGOMERY.