Every professor for whom you write a paper will have his or her own advice on revision. One helpful way of thinking about revision comes from A Community of Writers by Peter Elbow and Pat Belanoff. They use these phrases to talk about three levels at which you can alter a piece of writing:
When you've finished your work, step away from it so you can come back with fresh eyes and consider whether you need to make any of these types of changes.
Alyssa Hurzeler, "Revision," Expository Writing II, p 165-66.
By reviewing your paper, you can determine whether you need to change the "muscles" or the "bones" of the paper, as described in the box above. Here are a few approaches:
Finally, no paper is complete until you've given it a final proofread.