I have studies peoples legs for a while now, in terms of body language. I have found that when a person is feeling un easy or anxious they will tend to bounce their legs up and down (this is more common in men). However for women when they are feeling the same they can move their feet in circular motions when their legs are crossed sat down.
I have also found that when in a non interesting conversation the person will not face you square on, they will stand slightly to one side or face the way they were heading. However once they feel more engaged or interested in the conversation the person will naturally turn to face you square on. It is interesting when you notice this in real conversation because you can determine how the conversation is going for the opposite party. This can work both ways. For example, the person may face you square on at the start and once they feel the conversation isn’t going anywhere or they aren’t interested anymore they will then start to turn away from you slowly.
I encourage you to try these out when you are in real conversation as most people will do this wether it be speaking with friends or family or speaking to a complete stranger, most people will do this and it is very interesting to observe