Although you should remember to bring all potentially useful documents, it is also important to remember that the visa interview is a conversation, not a document review session.  The best thing that you can do is to clearly articulate—

1. Why you want to go to the specific school
2. What you plan to study
3. How you plan to use your education when you return home.

Be ready to cover this information in no more than about 3 to 5 sentences, and practice saying those sentences with family and friends until you become comfortable with the English.

Here are some of the types of questions that you might get asked:

• Why have you chosen this university?
• Who will sponsor your education?
• Why don’t you study this in your own country?
• Do you intend to work in the United States? (Remember that only very limited amounts and types of work are permitted under student visa status.)
• What are your plans after finishing the degree?
• What was your TOEFL score?

Also important, as for any first conversation, is to dress nicely and smile. 

In regard to documents, it is better to have too many documents than to have too few. Just keep them in order so you can find whatever you may need!