This is all good advice!

I want to add that body language is a fantastic tool, but you can't just use something like the feet to get a complete idea - you have to look at the person's whole body.

As an exercise, go to a party or a concert sometime and spend some time looking at people's body language - ignore their faces and look at how their bodies are arranged, whether they use their arms to protect their bodies or to open up, where their bodies are wanting to go.

It really isn't very hard to learn and once you know, it makes it very obvious where people are at. And that's just a good thing - it makes you more sensitive to what others are feeling.