Depends on what's your learning type. You have several approaches that you can try. For this exercise, I would recommend: The Definitive Book of Body Language by Allan Pease and Barbara Pease.
- Approach 1. Browse (not read) the book from cover to cover 2X. Go to a public place and observe people. Flip through the pages of the book when you see a familiar nonverbal cue and look for what the signal means. Read it. Do this for one week.
Now, read (not browse) the book again from cover to cover 2X. Next, interact with people for just one minute. Keep the interaction down to just one minute. After every interaction, remember that one minute and secretly consult the book for what the body signals mean sequence-by-sequence. Do this until you master the entire Body Language book. You have to consult the book in secret as people you know will get offended when they realize you're trying to read their nonverbal cues right in front of them with a reference book on body language.
You can interact with people you know for more than a minute and consult the book later only for the nonverbal signals that you can remember. But for sarging strangers, keep the interaction down to just one minute so you'll get a faster learning curve.
Approach 2. Browse (not read) through the entire book. Next, focus on just one chapter and read it 5X. Write about what you've read and consult the chapter for accuracy and completeness of what you've remembered from reading the chapter. Do this 5X. Next, go to a public place and observe for the nonverbal cues that you've read about in the chapter. Every time you observe one nonverbal cue in that chapter, write it down and what it means. After writing the nonverbal cue down, try to do the same cue yourself whenever possible. Do this until you know the chapter blindfolded. Go to the next chapter and repeat the process. Do this for the entire book.
After mastering the entire book with actual observations of people around you, attempt to interact and interpret the nonverbal cues all at the same time. This will feel weird at first, but on your 10th or more interaction, reading body language will become very natural to you. At the end of each day of your interactions, always consult the book to verify and validate what you've seen. As you look at the illustrations in the book, do the nonverbal cues yourself where applicable. Doing this everyday for at least 21 days straight will help you master body language.
Approach 3. Get a learning partner, preferably your younger brother or sister. Play a body language game on an alternate basis. Read the book first at least once. Your learning partner will open the book at random and will do a body language cue from that page and then you guess what that means. Say (verbalize) the meaning loud enough like you're preparing for an exam or quiz bee. Consult the book if you're correct. Do this as often as possible until you remember so many of the nonverbal cues in the book.
Next, go to a public place and observe people. When you see a nonverbal cue, record your observations on your phone. Say something like, "Guy in blue shirt touches nose several times while talking to his girlfriend. He's lying." Or whatever you see. Do this everyday for one hour. Verbalize what you observe and record this on your phone. At the end of each day, playback your recording and listen to your observations.
