(a) You do not want other students to judge your position based on what kind of person they believe you are or based on their suspicions about your secret motives or hidden agendas; you want them to judge your position on its merits. The best way to get others to judge your position on its merits is to judge theirs on theirs. So begin with the assumption that other students offer their positions, arguments, and reasons in good faith, and proceed to examine them charitably. Do not assume bad faith on anyone's part until long experience allows no other possible interpretation.
(b) Your professor is not infallible, but he has spent considerable time thinking about the issues you are examining in his class, and he has developed professional opinions about those issues. Assume, therefore, that your professor has good reasons for what he asks you to read, write, or do, until, again, there is no other possible interpretation.
(c) Finally, assume that what you are reading is worth the effort to understand it. If you think that its argument is obviously wrong or that it has missed or overlooked obvious objections or problems, assume that you have missed something and go back to the text and look for it. Continue to give the reading the benefit of the doubt until you simply can do so no longer. And even then ask yourself what you can learn from it despite its flaws.
3. Practice. Reading carefully and writing well are skills, and, like other skills, they must be practiced. You must do them over and over again. When you make mistakes, correct them and learn from them. Pay attention to details: Why did the author use this term here or this metaphor there? What exactly--not approximately or "sort of" or "kind of," exactly--are the author's reasons for making the claim he does? When it comes to your own writing, revise, revise, revise. Go over your paper three, four, five times; in the morning and at night; let it go a day and then return to it. Do not be afraid to delete, cut, or globally rethink. There is perhaps no single more important key to successful writing than editing. Use it liberally.
4. Preparation. An old quip has it that ninety percent of success is showing up. I would say: Ninety percent of success as a student is preparation. This means reading the assigned materials, mulling them over, asking yourself what their strengths and weaknesses are, being able to give concise but precise and correct summaries of them--all before you step foot in the classroom. When class begins, you are then ready to proceed immediately to all the interesting philosophical, exegetical, and other deep questions.
5. Finally, purpose. Why, exactly, are you here? You need an answer to that question that is plausible. That means it will have to connect up with your goals and ambitions, it will show some awareness of the scarcity of your resources and your resulting allocation of them, and, most important, it shows that you understand that you are a rational and autonomous being and not just a lump of biomass. It is not necessary that you have a complete life plan worked out in all its details. But it is necessary that you have goals and have given them some thought. You are too precious, and your time, talents, and treasure too dear, not to bring your considered judgment to bear. There are many different lives in which my class might play a plausible, if small, part, and thus many different reasons you might be in my class; but please do not let it be that you simply had nothing better to do. You owe me, and, more importantly, yourself, more than that.