It's a well known fact that most people will quickly identify an old friend from high school as "friendly" even if they've only just met them. Likewise, many people will say, "Oh, it's so great to meet you" without ever having met them in person. Why is this? It's all about social perception and reading people.
Because we learn to talk to people all day long and we are exposed to thousands of different people each day, we often assume that most people look like the friends we have in our class or around our work group. As a result, we unconsciously see them as good, friendly people. Conversely, we may think someone looks "unhealthy"disgusting" because of something they're wearing. We simply cannot differentiate between a healthy and an unhealthy person. If you've ever seen someone in public with clothes that were too tight, you know how easy it is to be fooled by that.
So how do we avoid the easy way out of learning to recognize people? The best way is to start by having some basic skills in social perception.
For example, a simple way to start developing your skills in reading people is to ask yourself how the person's body language is. Think about the clothes they're wearing, the posture they're in, how they're holding themselves and so on.
Another important part of learning to read people is to develop some degree of rapport. How do you feel when someone else that you admire does something that makes you feel good? Notice how you react. Do you smile or laugh?
Remember to be a good listener. When you listen attentively to someone's conversation, you pickup their tone of voice and your own, so that you can adjust your own tone so that you are responding to what the speaker is saying rather than them speaking to you. In other words, you're listening to what they are saying and not to you.
When learning to read people, pay attention to subtle cues. What words do they use? Is the tone of their voice a little flat or is it quite friendly?
These things can be determined through research on the human personality, but it can also be determined by personal taste. If you notice that the person you're talking to seems more serious, then that person probably comes across as serious and has something to say. But don't automatically assume that they are a very serious person just because you like their personality.
By the same token, if you notice that they're talking about their hobby, their hobbyist or their pet, and are talking in a general direction away from you, then they probably have a hobbyist or pet. Conversely, if you notice that they are talking about something they know a lot about, and they're either talking towards you or away from you, then they probably know a lot about something or are very knowledgeable about something.
You'll also notice that many people will draw attention to things about themselves that you will probably never see them do in person, such as using body language to make an eye contact with you. Pay attention to body language and tone of voice. Then you can infer certain things about that person from these clues.
Most people will tell you that the easiest way to learn to read people is through word association. This is because everyone has a word associated with something and when they are talking, they will more than likely use that word to identify that thing.
For example, if you are asked "what are some questions for which you would like to speak," you will want to answer "I want to speak about pets" because you associate the word "pet" with the activity of speaking. In addition, if you were asked "What are some questions for which you do not want to speak?" you would probably try to answer "I do not want to speak about pet issues."