Use the history research toolbox , on our website, for hints on everything from finding a topic to citing difficult sources. The classic style book is Strunk and White's Elements of Style . Read over their suggestions. Another useful source is Mary Lynn Rampolla's A Pocket Guide to Writing in History. Often, professors are glad to read over rough drafts and make suggestions.
Good papers are usually the result of writing and much re-writing.
Use a plain text 12 point font and do a paper of the length that is assigned. Unless you aspire to be William Faulkner, write concisely, clearly, and simply. Focus on making your points to the reader. Read at least a portion of your paper out loud to yourself. Write a rough draft and ask your professor to look at it.