​Putting the text in a another format can make it different enough to see that missing quotation mark or misspelled word. Fortunately, the final version of the text for proofreading is usually the galley proof or typeset. So right away, the words are presented in a different format. It's amazing how many oopses pop out at you when the manuscript page finally looks like a real book.

Printing out the typeset also adds a fresh dimension to proofing. Not only is it a different format, it requires a physical interaction such as having to handle each page and being able to scribble notes and corrections. You can also put pages from different parts of the book side by side, instead of awkwardly scrolling back and forth.

Reading out loud, either from the screen or printed copy, forces you to pay attention to each word and is great for not only finding awkward sentences, but missing or transposed words.

Another favorite proofing method is to have the computer read it to you as you follow along. Like reading aloud, you are forced to listen to and look at every word.

Reading the book backward. Whoa. What? This is a trick I learned from a science fiction author many years ago. He was with a major publisher that, at that time, still produced galleys like the one to the right. This author would proof it by starting at the end of the book. 

The way it works is you read the last sentence. Then you read the second to the last sentence, etc. What this does is force you to not get caught up in reading the book. Isolating each sentence allows you to  focus on finding errors without being hampered by context.

So give one of these methods a try on your next adventure in proofreading. Along with helping to spot the elusive errors, they may make proofreading a more pleasant experience for you.