It should be immediately clear to the consular officer what written documents you are presenting and what they signify.
Not All Countries are Equal
Applicants from countries suffering economic problems or from countries where many students have remained in the United States as immigrants will have more difficulty getting visas.
Your main purpose in coming to the United States should be to study, not for the chance to work before or after graduation.
Dependents Remaining at Home
If your spouse and children are remaining behind in your country, be prepared to address how they will support themselves in your absence.
Maintain a Positive Attitude
Do not engage the consular officer in an argument. If you are denied a student visa, ask the officer for a list of documents he or she would suggest you bring in order to overcome the refusal, and try to get the reason you were denied in writing.
Visa Interview Advice (You can print out this information.)