Proofreading should be done when you are most alert and when you have plenty of time to focus. This allows you to carefully look over your writing and to catch errors you might otherwise miss. If your work is done on the computer, print it out. First, slowly and thoroughly read the work aloud and then silently. This can help you make sure you didn't miss or repeat any words. Proofread the body of the text, then the headings, which are prone to errors because they're not usually focused on. Concentrate on one area at a time by using a blank piece of paper or a ruler under each line as you read it. Use your finger or a pencil to point to words and read them one at a time. Don't proof for all mistakes at once. First, concentrate on spelling, then grammar and so on, keeping track of errors that you make frequently.
When editing content, you should ask yourself if you have answered the questions who, what, when, where, why and how. To check if your facts flow in logical order, highlight the sentences that answer these questions. Assess the overall construction of your paragraphs, looking specifically at length, supporting sentences and topic sentence. Make sure the procedures are in order when writing about steps and that they are complete and accurate, and check that images are right-side up. Learn how to fix errors that you typically make so that you can learn to avoid them. If proofing your work on the computer, use the "Find" function to look for any of these mistakes. If you're not sure about something, look it up.
When checking for spelling, which is the most easily corrected error, don't rely on your computer's spell-check function. Do your own spell check since spellcheckers don't know the difference between there, their and they're and you may have used them incorrectly. Use a dictionary if necessary and be careful of words and homonyms (words pronounced the same but spelled differently) such as to, too and two and your and you're. To help you focus on the sentences and spelling of words rather than the content of the paper, read it backward.
Always double-check even if you're sure you're right. If possible, have another person read the document out loud to you. This helps you to catch any mistakes, wordiness and awkward-sounding phrases that you might have overlooked. Double-check for unusual fonts, proper names, page numbers, header and footer material, and words that are often interchanged such as or, of, it and is. Make sure that your word usage is correct, such as when using "affect" and "effect." Other things to double-check include sentence fragments, run-on sentences, subject-verb agreement, sentence structure, parallelism, apostrophes and other punctuation.