1. Read through the entire manuscript (ms) once, searching for plot or character inconsistencies.
If you can read through your entire ms in one sitting, you're more likely to find those holes or irregularities in your writing.
2. Go line by line, sentence by sentence, making sure each one is phrased the best way possible.
When I do this, I bounce around the ms. (It helps me focus on that particular sentence.) I just use the highlight tool to keep track of the places that I've covered.
3. Read your work backwards (start with the last sentence and work your way to the beginning).
This will help you find sentences that may run on, or comma splices (two independent clauses that are connected with a comma). This also forces you to slow down and read what's really on the screen as opposed to what your mind thinks you've written.
4. Read your ms out loud.
This helps with voice issues; you can also determine if your dialogue sounds natural. It's easier to focus on the pacing and flow when you read your own work aloud.
5. Use the MS Word "Find" feature to check for inconsistencies.*
I search for characters' names to verify spelling; I search for descriptions (blue eyes) to make sure the character descriptions are consistent; and I search for linking and "being" verbs, to see if any can be eliminated (among other things).
6. Print your ms out.
Proofread. Rinse. Repeat.
7. Have someone (or something) else reading the ms back to you.*
You don't know how many "a's," "the's," or "to's" I've missed in proofreading (even after several rounds), but caught when the computer didn't "read" what I thought was there back to me.
These are the highlights, but you can read the old post in its entirety here.
*Since the original post, I've started using Scrivener for my writing. This software includes search and find options, and will read selected text out loud. My love for Scrivener knows no bounds.