Disclaimer: The following is based purely on personal experience. I have no real evidence to support my arguments.
My brother once told me that empathy is a skill. For a while his statement didn't make sense; I firmly believed that understanding the feelings of other people was an innate ability. As a child, I watched movies in which the protagonists were empathic and the antagonists apathetic to other people's feelings. Because that difference correlated with the distinction between good and evil--and I assumed that people were born good or evil--I concluded that empathy was an innate ability.
However, through some introspection, I've finally understood why empathy is a skill.
First, it requires adept abstraction. To be empathic is to resonate with another's feelings. Such resonance can only be clearly established when one removes distractions such as race, gender, etc. Those distractions are problematic because they entail bias, which can of course skew perspective and so an understanding of someone's feelings. Hence, abstraction is essential to empathy.
Second, one must rectify the language of one's mind. In particular, one should try to change the way we perceive people through language. One way of changing one's mental language is to substitute words that imply division among people with words that are much more general. Suppose you see a homeless man trying to catch his runaway shopping cart, which is full of his belongings.Assuming that you already have some empathy, you may say, "I feel bad for that man." Instead of explicitly calling that person a man, try to say, "I feel bad for that person." "Person" differs from "man" in that the former is free of unnecessary distinction. After all, should you feel bad for someone in a predicament because you sympathize that "man", or because you sympathize with that "person"?
This distinction does seem meaningless at a glance - after all, they're just words, right? However, I believe that since we think with language, our choice of words regarding our perception of people is crucial to impartiality--which is in turn essential to empathy. In the above case, explicitly describing the person as a man may not have any immediate consequences for empathy, but a few subtle differences most likely go a long way. In training one's mind to explicitly describe people as people, one can start to forget about largely irrelevant issues and can thus easily empathize with others. Hence, the way we explicitly describe people in our minds can affect the way we perceive them.
In conclusion, the best way to strengthen your empathy is to internally describe people with general words and abstract people as much as possible.
I hope I made sense. >_> I posted this "editorial" here because I want some constructive criticism of my arguments, even though they aren't based on any evidence besides personal experience. Also, I'm not asking anyone to help me write better, but if anything is terribly written, I'd appreciate it if you let me know.