- Put yourself in their shoes
- Think of times you’ve been in a similar situation and explain your reaction
- Can the behavior be explained by a more “universal” model than a person-specific one?
- How are they empathizing with you, given they are projecting?
- How are they empathizing with you, given what you know about how they perceive others?
- What successful model have you used to explain similar behavior for similar people?
- Is your conclusion affected by your attitude towards the subject?
The problem is the repeatability. Social skills, by their very nature, require interaction with people. And people are unpredictable; at least, until you have good enough social skills :p.
The closest I can come to an exercise regime suggestion* is to go into bars, coffee shops, or other gathering places; and look around for a person (or people) who seems bored, lonely, or otherwise in need of company.
Go up to said person(s) and greet them in a manner you deem appropriate. If it works; you just correctly judged someone's state, you approached them in an acceptable manner, and you now get to converse with them (giving you practise on other social skills). If not; consider why not? Did you misread their state? Did you approach them in an unacceptable manner? What should you try differently next time?
*(and something I actually did, that seemed to help me personally: in fact I met my girlfriend due to this practise)
How did you manage to do this without garnering a reputation as that weird person who always starts conversations with random strangers, who you shouldn't bother responding to because the only reason he's talking to you is because you happened to be there when he was?