Effective editing is done in three steps, in sequence, because you look for something different each time.
Frustrated writers often read their copy again and again, only to discover they missed something, and they cannot imagine how. It’s because they try to accomplish too much at once. Reading it once, running it through the spelling checker, and hitting the “send” button can lead to embarrassing consequences.
The first time through is an overview. You are looking only for glaring flaws: information that is glaringly absent or information that is disorganized and needs to be repositioned. Resist the urge to change grammar and punctuation mistakes; this is not the time to do that. Instead, stay focused on the overall message (or article). Does it all make sense? Does the body support the opening paragraph?
On your second reading, look more closely at paragraphs and sentences. Does each one flow logically from the previous one? Are the words and sentences clear? Are they tightly written? Are the details specific?
The third reading is what we know as proofreading. Proofreading and editing are not the same thing; proofreading is the final step in the editing process. This is when you focus on line-by-line examination for errors in punctuation, grammar, and business-writing style. Avoid making the common mistake of looking for these flaws the first time through. The problem with that is that you might have bigger problems in the document, and you won’t notice them because you are preoccupied with misspellings and possible grammar mistakes.
The late Don Murray, once the dean of American writing coaches and the person who taught me the most of about writing end editing, introduced the three-step editing process.