One of the greatest abilities an author can have has nothing to do with learned writing skills. I'm not sure it can even be learned, although it can probably be developed to some degree. I'm talking about empathy.
Empathy for Characters
We have to successfully communicate how our characters feel and how they relate to the world. That means we have to be able to see things the way they do, understand why they feel the way they do, and communicate those feelings. Unless we're writing our autobiography, that means we have to delve into the inner workings of somebody who is not us.
We have to understand the inner workings of not only the characters we like and agree with, but those we don't. We need to understand our "bad guys" and why they are how they are, and how they believe they are actually doing what's best. That means we have to be able to see the world from other points of view, and understand (or try to understand) how others can see things the way they do.
This is difficult. Most people operate from a basic belief that they are, for the most part, right, and that those who see things differently are obviously flawed. Of course, those "flawed" people have that same point of view and believe they are basically right and you aren't.
Just like no two living people see the world exactly the same way, each of your characters has a unique set of perspectives that shape his or her point of view. You don't have to agree with all the various points of view in your story, but your characters will seem more real if you at least try to understand what makes each character tick, why they feel the way they do, and why they believe that they are right, then communicate each characters point of view as if they are right, at least from their own perspective.
Empathy for the Reader
To create a good experience for our readers, we need to understand how they will see the characters we create. We have to understand what keep speople reading. More importantly, we need to understand how they feel so we can manipulate their feelings. A successful book tugs at heartstrings and triggers fear responses and joy responses. The best books fool our brain so that we actually experience the emotions the characters are experiencing.
We can't assume that because we feel what our characters feel, that our readers will. We bring a lot to understanding of our characters that might never successfully reach the page. That's why we have to look at our stories not only from our authorial perspective but from the reader's. That's the only way to make sure we're successfully communicating what we want the reader to feel, not just what we think we're saying.
To develop empathy, we need to learn how to see beyond our own experience. We can learn a lot by reading and by simply paying attention. If we disagree with somebody, we should try to figure out how they could possibly have an opinion so distant from our own. If we see an accident or watch somebody suffer from a terrible illness, we should try to understand how the victims feel, and how those around them feel.
Many writers do this naturally. Writers are often excellent observers who have the ability to understand others different from themselves. People who have those skills are better able to write stories about other people. But whether it's easy for you or not, every writer benefits from deepening their own empathy, not only as storytellers but as human beings.
We are all constrained by our own perspectives, so we'll never get another's feelings and perspectives exactly right, but as long as we make a strong effort to do so, we can write convincingly and play with our readers. Our books will be much better for it.