So what are some of the things a writer should watch out for when editing their own work? I don't mean the obvious stuff such as typos or blatant grammatical mistakes, but more the subtler aspects of writing, such as a clunky way of wording things.
Read it out loud. Maybe even mimic your characters' accents or whatever when you're reading dialog. There will be a lot of places where you stumble over the words because it just isn't natural. Fix those. When you introduce a new location, check to see how much or how little you bothered describing it. I often find that my locations aren't described at all, which can be annoying for everyone involved. Same thing applies to characters, but to a lesser degree. That's all I thought of. >.>
Leave the manuscript alone for at least a month before you edit it. Fresh eyes are the single best editing tool. I second what @archer88i said about listening to your manuscript, but I'd recommend using text-to-speech. The software won't fill in missing words or skip over typos like a human would, and the robotic voice helps you identify rhythm and repetition problems. I use http://www.fromtexttospeech.com/, which is free. Things I look for, apart from typos: - Words I know I use too much. 'Just' is one of mine. - I also search 'said' and see if I can get rid of any dialogue tags. Redundant tags are annoying.
In addition to reading out loud, someone (maybe on @zoupskim's thread?) mentioned using text to speech to have your work read out. When you read out loud, you can sometimes (or at least, I can sometimes) get caught up in the rhythm of your work and overlook errors like like doubled words, but the text to speech will highlight those. Doesn't work as well if you're writing fantasy where Z'Grhyrbl smote Gz'hraboalyd's head off, of course....
I look for clarity in my prose. That's about it, really. It might sound really simple, but it's not. At the same time it really is the most important part of your work. Without clarity you have nothing.
I think timing is another that should be mentioned. There are mistakes people make when they feel they've been writing forever and they write this very dramatic scene where a character dies thinking its deep into the story when in reality it's only 70 pages in. I've experienced that before on my earlier stories. Even if it feels like your story is deep into it, readers read quickly so whatever emotion/mood you want to convey is likely not as powerful to others if the story doesn't take time to explore the character/moment. And that's all I gotta say about that.
I read everyday. I read at night in bed before turning out the light. Because I write as much as I read, I've developed a habit of editing. Habitually, I want to edit the books I read. Like a strung-out junkie who gets his fix from editing, I can't stop. Don't just read the works of respected writers. Read everything. Look for things you would word differently. The most common mistake I see in other's writings is wordiness. So many sentences can be strengthened by replacing phrases with a single, stronger verb. Sometimes a simple sentence like He ran is all that needs to be said.
Definitely this. Taking a break will also reduce (but not eliminate) the tendency to skip over things, as mentioned below. The current version of WORD has a built in read-aloud feature within EDIT mode. It's easy to use and saves you the trouble of having feed stuff into text-to-speech programs. I'm currently going through my WIP with it, and it is extremely helpful. On other thing. If you find yourself skipping forward at a given point, thinking. "yeah, I know all this", that's a red flag. Maybe that segment really doesn't hold your interest, and if it doesn't hold yours, it won't hold the reader's, either. Excise! Good luck.