if you are talking live i would suggest reading up on a few "body language" books (poker or not related).
- Joe Navarro - What Every Body is Saying
- Lieberman - Never Be Lied to Again
- Pamela Meyer - Liespotting
- Paul Ekman books
- Caro - Caro's Book of
poker tells
- Navarro - 200 Poker Tells
- Elwood - Reading Poker Tells
could be a start and then go (google) from there