Read your paper out loud to see if the wording flows naturally and that the prose makes sense.
Remove extraneous wording. If you can say something in six words instead of ten and still get the same information across, go with the simpler version.
Add important details that may be missing. If a fact is missing or something is not adequately explained, add the information.
Verify all your facts. Your research needs to be as current as possible, because new studies could refute older information and outdate your paper.
Search for redundancy. If you are repeating your facts multiple times throughout the paper, the paper will be longer than it needs to be and can be a chore to read.
Ask a friend or someone knowledgeable in the subject to read your paper and let you know if there is anything that is incorrect or unclear. A second opinion is very useful in getting your paper to stay in top form.