This checklist stems from typical issues that I have seen in student papers. I’m keeping it here, instead of my language blog, so that I can add to it over time. 

• Does every paragraph in your paper contain a topic sentence?
• Does your argument make sense if you read only the topic sentences in your paper?
• Does your paper begin with an introduction and end with a conclusion?
• Do you only tell the reader your argument, or do you devote much space to showing him what you mean with examples from the primary sources?
• Have you cited your sources?
• Will the average, educated person be able to understand your paper? Or will only someone in your class understand it? Write for the educated general reader, not your professor. Include bits of background information where necessary.
• One way to test how successfully your paper conveys your ideas: Have someone read your paper and tell you what it is about. Do they get it? Or are they receiving a message that you did not intend to convey?
• Did you write your essay in the past tense? If not, change it to the past.
• Do you use the passive voice? Try not to, because it allows you to avoid the question of agency, which you are not supposed to do. Your reader does not just want to hear that something was done. He wants to know who did it.
• Do you rely too heavily on the verbs "to be" and "to have"? They are useful, but there exist many other verbs in the English language too. (Example: The first sentence in this checklist originally read "Does every paragraph in your paper have a topic sentence in it?" Does not the new version sound better?)
• Do the words you use mean what you think they mean?
• Can you make the same point with fewer words?
• Do you qualify general statements where necessary with phrases such as some, many, most, a few, a majority of, and a minority of? Or do you mistakenly lump all Europeans into one pot?

Make sure you also read the Ten Commandments of Good Historical Writing by Theron F. Schlabach