Every once in a while I hit on something while I'm critiquing, and something that I've been learning, I can suddenly put my finger down on just what's wrong and why. I figure I might as well record it. So, today's:

There a balance between getting information across through exposition and through dialogue; exposition can be an info dump and bore the reader, but at the same time, to make dialogue sound natural, it's generally not a straightforward explanation of the information you're trying to convey. I find authors do it best when they go back and forth; a couple lines of dialogue, and a couple lines of narrative to explain the context of what was just said.