Something should happen in every single chapter to further the plot.
Now, I already knew this before, but it's quite easy to slip your mind when you're actually writing a story. You get caught up in your character, the world, the story and just the general awesomeness of writing your book, and totally forget that this chapter is supposed to have something important in it. Happens to me all the time, happened to me earlier today. I was writing along and then was all like "Oh, wait. What's furthering the plot here?"
Now, I went to one of my most favorite books of all time to scan through the chapters and see does something very important happen every single chapter. I went through Harry Potter and the Sorcerer's Stone. And something important does happen every single chapter. Something that furthers the plot. Now, when I was writing earlier I was pretty much just thinking, "Okay, introduce characters, setting etc. until I get to the first twist, however many chapters that takes."
I can't do that though. I can't have chapters there just to be there. They have to do something for the plot. I can't have a chapter in my book just because it's interesting or funny, unless it furthers the plot. It's a bit frustrating for me but at the same time it makes things easier cause I know that each chapter has their own individual mission of getting the plot a bit further, instead of just acting as separators within the book.
When I forget this kind of stuff it makes me feel a lot like this: