Below I've outlined some generally good advice for proof reading and editing your papers. These are techniques that I use and have found useful. Integrate them into your own writing process.
1. Give yourself time. If you finish your paper at 1:00 am the day it is due, your mind will be Swiss cheese and you will not be able to look at your work critically. If a rooster is crowing somewhere in the United States, you have not given yourself enough time.
2. Really, give yourself time. Greatness does not come from burning the midnight oil. Grammar and punctuation mistakes, leaps in logic, and lowered grades do.
3. Give yourself a day in-between completing your paper and looking it over. When you proofread your paper just after you've completed it, you lack the critical distance necessary to really look over your paper. Your words will make sense to you because your ideas are fresh in your head and are still a part of your thinking process. Other people, however, are not privy to your intimate thoughts.
4. Read your paper aloud, preferably to a friend (you can buy them coffee later). Reading your work aloud will make re-reading your paper a fuller experience. You will read slower and your ear will help you pick up mistakes your eye will miss.
5. Have someone else look it over for you (again coffee). A fresh pair of eyes will do wonders.
6. Read your paper backwards. Backwards paper your read? No, not like that. Start at the end of your paper and then work your way back paragraph by paragraph. Often times, we start strong and end weak when we write. Proofreading backwards allows you to follow your progress and make improvements. It is also a good tactic to take after you've gone through your first and second read through and find yourself skimming the first part of the essay or getting tired by the end of it.
7. Compose a reverse outline. Not sure if your paper makes sense? Make a reverse outline of your paper, highlighting your main points. You might find that you are missing a step in your thinking.