Even if your professional aspirations lie elsewhere,proofreading is an incredibly useful skill for an author to have. Here are some tips to get you proofreading like a pro:

• The dead and live copy should be side by side. Dead copy on the left side, live copy on the right. We read from left to right, and whatever we read first, looks right.
• Use some kind of a guide (a ruler or another sheet of paper) to keep your place in the dead copy, and use your pencil eraser to follow along in the live copy—you can turn it around when you need to mark something.
• Strange but true. If possible, proofread under incandescent light rather than fluorescent. It’s less tiring, and the flicker rate is faster, so your accuracy rate will be higher.
• Use a brightly colored pen or pencil to mark the manuscript. Your publisher may prefer one or the other, so check with them.
• Go slowly. Remember that you’re reading character by character, not word by word or sentence by sentence. You’ll figure out how many characters you can pick up and check at a time. Some proofreaders read out loud, some will even read short passages, like flap copy, backwards. Some will even look at pages upside down, if they’re focusing on type. It doesn’t matter what you do as long as you’re reading slowly and paying attention.
• Note changes in the margins.
• At the start of every page, look quickly at the page and see if anything pops out at you. It may be easier to see things like uneven margins and bad spacing and alignment errors in a quick pass like this one.
• If you’re not sure about something, look it up. Warning: There’s a fine line between madness and terrific proofreading—if you stare at any word long enough, it falls apart. Everyone who’s done a character-by-character read is familiar with the sudden feeling that no word makes any kind of sense at all, especially the word “until,” which looked absolutely normal five minutes ago and is now the most ridiculous set of sounds in the English language. This is normal and will stop happening the more you proofread.
• Keep an eye out for end-of-line word breaks, and check the hyphenation in the dictionary or a guide to word division if you’re not completely sure.
• After your comparison reading is done, read the live copy by itself. If something looks wrong or weird for any reason, check the passage against the dead copy.
• You may do multiple reads: one to make sure all the running heads and folio information (the author name, page numbers, chapter title, etc. at the top of every page) are there and accurate, for instance, and another to make sure that all the lists are correct—in the right format, properly aligned, and in the right sequence. Or one to check all the end-of-line word divisions.
• When you find an error, reread the whole sentence. Everyone has a tendency to assume that there’s only one error per sentence. At any rate, the second error is always harder to catch since your brain is off having a little victory party for catching the first one.
• If the mistake you find was made by the typesetter—if it’s something that’s correct in the copyedited manuscript—write the letters “PE” in the margin and circle them. PE stands for printer’s error, and it’s crucial that you mark these when you find them. Anything that isn’t marked is counted as a AA, or Author’s Alteration, and you will be charged for them, according to your contract. Printer’s errors are corrected free of charge.
• Don’t get lazy about the non-text stuff: check every table, equation, and caption as carefully as you do the text. If the table is meant to be read across, read it down; sometimes it’s easier to check if you’re reading out of order.
• Check every page reference to make sure it’s correct, whether it’s in the text or in the table of contents.
• Check headings and titles really carefully. They’re tricky precisely because they’re authoritative. How many times have you looked at an awning or a title or text in a letterhead and thought: “How could they possibly have missed that?” Everybody takes it on faith that nobody would be stupid enough to misspell the name of the restaurant, so they don’t check.

There’s a beloved story among proofreaders in which a university handed out diplomas with the name of the school spelled incorrectly. Nobody noticed, even the people responsible for double-checking the names of the graduates. None of the graduates noticed until much later either, but that’s another story entirely.

• Always, always make a copy before you send the corrected page proofs back to the publisher and label it “Proofread page proofs” with the date.