10. Your Audience
In your paper, you must demonstrate that you have mastery of the philosophical issues and arguments that you are discussing. The best way to go about doing this is by pretending that you are writing, not for your instructor, but for someone who knows absolutely nothing about philosophy or the course that you’re taking. So, as James Pryor puts it,
Pretend that your reader has not read the material you're discussing, and has not given the topic much thought in advance. This will of course not be true. But if you write as if it were true, it will force you to explain any technical terms, to illustrate strange or obscure distinctions, and to be as explicit as possible when you summarize what some other philosopher said.
In fact, you can profitably take this one step further and pretend that your reader is lazy, stupid, and mean. He's lazy in that he doesn't want to figure out what your convoluted sentences are supposed to mean, and he doesn't want to figure out what your argument is, if it's not already obvious. He's stupid, so you have to explain everything you say to him in simple, bite-sized pieces [while also illustrating your points with helpful examples]. And he's mean, so he's not going to read your paper charitably. (For example, if something you say admits of more than one interpretation, he's going to assume you meant the less plausible thing.)