You've probably heard the saying go something like this: "less is better."
It's really true actually.
As I plow my way through Spirit of Orn, I am finding myself on the cusp of transition. Earlier in my book, the chapters were really short, so I found myself having to add material and expanding upon conversations and interactions between the characters. (It's good to ask yourself questions like, "What would the main character say in this particular situation?" It's an easy question to ask, but I don't think we like asking ourselves this. It just means more work. Be brave! That's all I can say.) Now that I am at the part of the book that was written largely when I was a better writer, I am looking at long paragraphs of information, which begs the question, "How does one prune?"
I look for three types of things to prune when I am writing.
#1: Old Plot/Hat: When you go through in the second and third revisions the easiest thing to get rid of are things that are no longer happening in the book. For instance in my book the main character had in his possession something that I wrote out in the third revision. So now I have to keep my eyes peeled for any description of that item. This is probably one of the hardest forms of editing. It requires that you keep track of the plot in all of it's fine tuning and nuances. Write down the things you change if you can.
Another thing you can get rid of are just old things that you no longer have use for. In the last revision of Spirit of Orn, my main protagonist was very hyperbolic so I've had to tone him down since starting the third revision. This is easy. You'll know exactly what to get rid of. The reason for this is because the character now in your head currently will undoubtedly be much different from your previous version. You'll know what to change pretty easily.
#2: Word Economy: Less is better. If you can find descriptions of things or events and can boil them down into more concise descriptions, just do it. I think we have been taught implicitly that the stories we write should be articulate and flowery. After reading Shakespeare and all my early modern stuff like the ballad poets, I got it into my head that this is the way I wanted to write. This isn't a good idea however.
Just write simply. Shorter sentences have power, and clarity. If you can say what you want in ten words or less rather than what was originally stated in your draft, then by all means change it. I think E.M. Foster is really good at this. Look at the way he describes his characters in A Passage to India. Some of his sentences are profound, yet so simple. Take a look at that book sometime and let each of them hit you. It's awesome!
#3 Descriptions: This falls in line with the point above, but I thought I would stress it here. Do yourself a favor and take a look at your descriptions. What I like to do Is ask myself this question: "Do these descriptions advance the plot or the character?" It's a good question to ask yourself. There were lots of descriptive details in my book that I noticed could be deleted and nothing integral would have been lost. It's good to trim this stuff out. I mean, I can understand the point of creating a living, breathing world with superfluous details, but just be prudent. Somethings are better left unsaid, and implied.
Take these thoughts into account as you are writing, and I promise that you'll see improvement. I myself learned most of these points from authors caught in the throes of interviews and other forms of self-disclosure. Thus far they have been very helpful, and I hope that they remain helpful for you!