So ensure readers can see what your characters are like. Show reasons for the characters being the way they are (a good villain will elicit sympathy). Take us into the thoughts of your characters so we can see why they think the way they do. In seeing things from their perspective, we can see what drives them (and the great thing with this is we don't have to agree with that perspective either. We just need to see the character really believes in what they are saying and doing).
In seeing what the characters do, we don't necessarily see everything. After all in any story a character will only see so much - there will be things they don't know. But we will go on the journey of the story with them and will understand their reactions so much better if we know where they are coming from.