It's the part of the writing process that often gets short-changed. It's also the part that separates the professional from the mediocre. Final editing is usually most effective if done on hard copy rather than on a computer screen. You can ask a colleague to read your document and point out any areas that need special attention.
Teachers often arrange for students to work in partners as peer editors.
Just remember that it's NOT up to you or your partner to make each other's corrections. That's the writer's job. It's preferable to do final editing on hard copy. Whatever editing routine you're using, you'll always need to have your references close by. Hard copies of a dictionary, thesaurus, and writer's reference are still indispensable, although you can find many computer-assisted writer's aids now too.