I think that the hardest part of writing is unlearning everything you know and then relearning it with a completely different perspective.
For example, when I first started writing stories, I wrote them exactly the way I would verbally tell them to someone. As a result, my writing was riddled with telling phrases like ‘he felt/saw/heard/knew,’ or ‘she noticed/realized/thought/etc.’ When verbally telling someone a story, the person you’re telling just wants to know the basics of what happened so he can get to the climax as quickly as possible. So, when we verbally tell a story, we tend to focus on what’s happening on the surface.
New writers tend to take this practice and apply it to their writing. I did. It’s what I knew, and, verbally, it worked. But it doesn’t completely work on the page, and it took me several years to figure out why.
When we write with the intent to show the reader what is happening to the main character, we are focusing on what’s happening outside the character. This isn't necessarily a bad thing. It's good to see what's happening very clearly, otherwise the reader will be confused as to what's going on. But we can't leave it at that. To get a fully rounded experience, we need to know how everything affects our characters. In order to know this, we need to see what goes on inside the character. In other words, we need to write from the inside out.
This is something that *must* be done in first person, because that’s its nature. First person is inside the head of the main character, so everything the reader sees must be from the perceptions, biases, misconceptions, and assumptions of the character. Everything I see gets interpreted through my own experiences and perceptions—as a result, there is an inherent bias, whether I intend it or not, simply because I have to process information based on the things I know. The same is true for characters written in first person.
So, when writing a character in first person, it’s best not to focus on the main character’s exterior, especially facial expressions, when exterior events affect him in big ways. These observations are fine for minor characters because we're not supposed to be in their heads. But, for main characters, this doesn't work well because it takes us out of his head and makes us observers rather than letting us experience her situation for ourselves. Instead, focus on what’s happening inside his head. What emotions are going through him? What thoughts do those emotions trigger? Then, how will he act as a result? In other words, write him from the inside out.
Third person is slightly different because its nature is on the outside looking in. However, limited third still needs some of the closeness that first person gives the reader, but it's often not there. There is a way to get it, though, and the process is exactly the same as first person. As you're writing your story's events, insert some of your character's thoughts here and there. Not necessarily separated out in italics with s/he thought tags, but woven into the narrative itself.
Uh-oh. Mom was fuming. Cassie had really messed up. Would she be grounded for a month? Or more? If she was, then how was she going to meet up with Jason like she'd promised? If she didn't help him, then he was going to fail his midterms and suffer the beating of a lifetime from his father. She had to think of something.
The above paragraph is written from Cassie's perspective. We are given her particular perceptions, assumptions, and thoughts about the world around her and what might happen to her as a result of her actions. Essentially, we are in her head and the focus is on her from the inside instead of what she's doing on the outside.
If we experience the emotions and thoughts of the character, then we’ll understand his resulting actions and form a close connection to him. This creates a stronger and more enjoyable reading experience, which we all strive for. :)