How do you learn to read someone's mind?

That is not an easy question to answer... if you want to know if someone can hear your thoughts, exactly as you do (like Sookie Stackhouse on TV) the answer is NO.

If you think about it, even you don't "hear" your own thoughts in that manner. The human mind works much faster than you might think, we have thousands of thoughts running through our minds at the same time. It is very nearly impossible to sort them all out into individual trains of thought. So for an outsider, it would be like listening to five or six radiOS (not really on a solid or strong station) all playing at the same time.

There are people who can read thoughts, however they are usually single ideas, images, and/or emotions, strongly and purposefully "sent" to a person who is concentrating on the receipt of that single thought.

Yes. Some people actually can. Its a siddhi in transcentental meditation.