Chicago (Turabian) style is the most frequently used style for the discipline of history. It allows you to use either footnote or parenthetical author-year citation -- ask your professor which (s)he prefers. There is a brief online guide to citation using the Chicago style at the University of Wisconsin Writing Center.
Ellis Library also has a copy of the latest edition of the guide at Ready Reference Z253.U69.
Feeling lost and alone when writing your paper? Here's a friend. Steve Kreis, who got his Ph.D. in history at MU, has designed The History Guide, with good, practical ideas on finding and narrowing topics, putting together what you find in your research, and writing a good paper. (A side note: anyone considering graduate school in history should read Dr. Kreis' autobiography.)
Finally, here are a few ways to write an interesting paper:
1) Trace a change in a state of affairs and make a stab at explaining the change.
2) Relate an unofficial version of an "official story."
3) Contrast real life with a common stereotype. (Luther in film vs. Luther in sermons)
4) Compare a real-life situation or event with a theory of social life or change. How much (or little!) does this theory account for what happened?
5) Distill a pattern of thought or action shared by people in a time period out of the historical record. (Women were treated in X manner in Luther's sermons under B circumstances, but in Z manner under F circumstances)
6) Make up a typology, or finite set of categories, that makes complex data easier to comprehend. (churchgoers, charity donors, educators, self-made/lay priests as categories of religious participants across religions in 1500's Germany)
7) Compare and contrast two groups of people or two events that seem at first glance to be either very similar to each other or completely unrelated/different. Show what makes them similar and different.(ex.: Reformed and Catholic sacraments in 16th-Century German life)
In general, emphasize the unexpected: something appearing monolithic at first glance is really complex; something that seems to have "always been that way" actually evolved; a religion or government appearing to function from the top down actually experienced change from the bottom up; something appearing to be an effect is really a cause; something that appears as a cause is merely a correlation.