The following describes what I would ideally do (and tried to do back in the ancient times when I was a student) to prepare for an exam.
Different methods work for different people, and there's never time to do all that would be ideal to do, so if you are not doing what I describe below, don't panic!
A course will address various topics but usually give you only a passing acquaintance with each: a few lectures, some handouts, a tutorial discussion based on a rapidly read article or chapter. It's a good start, but an important point of revision is to go beyond this, to extend and tighten your grip on topics so as to enable you effectively, clearly, and rigorously to answer exam questions.
Here are some pointers:
1. A SCHEDULE
Perhaps the first thing to do is to compile a realistic revision schedule. Bearing in mind what revision it would be good to do (see 2 below), when each exam is, whether some courses require more revision than others, what other commitments you have, and so forth, pencil into a calendar chunks of time for revising each course, and perhaps even for revising key topics within each course.
It is a good idea at this point to list for each course the main topics the course addressed.
Preparing a schedule like this can be frightening, since it can seem to reveal that you've more to do than there's time for, but -- as I said -- that is always true, and true for others, and planning (quickly!) will enable you to make best use of what time you have. Don't panic!
2. READING and ENGAGEMENT
Here are some thoughts about what revising a topic might involve:
(a) If there's time, and a need, read more. Consult the course reading list and if necessary the lecturer to decide what it would be most useful to read in the time available, and then draw up a schedule for yourself.
(b) But, crucially, avoid revising only passively. Avoid, that is, simply re-reading handouts, notes, essays, and even the wider literature. In addition to reading, and taking notes, you need to somehow engage with your revision materials. This might involve all sorts of things:
When revising, I used to map the shape of the topics by producing something akin to flow diagrams on big A2 sheets of paper (one per topic), trying to sketch the shape of, and relationships amongst, the central issues and arguments on that topic -- identifying, for example, the three standard approaches to a question, and showing how the first has two versions, the second of which faces three objections, one of them --- say -- my own, and so on.
For me, grappling with the issues also involves (when I'm sure the men in white coats aren't around) walking around my room, engaging aloud in a conversation with myself on the issue at hand: "The attribute dualist will surely argue ... But then a materialist is surely going to come back and say ... But, if so, then the dualist will claim that a distinction has been missed between ...", and so on. Once I'm done, I note down and incorporate into my topic maps such useful moves or formulations that emerged.
Also decide in advance how best to formulate the more complex and central claims and theories, e.g. precisely how to define rule utilitarianism, or a reliabilist theory of knowledge, or semantic externalism. Commit these formulations to memory so as not to waste time in the exam.
Engagement can also involve sketching essay plans for potential exam questions (see past papers for some ideas). Decide ahead of time what line you want to take on some central issues, i.e. what positions you think you can most convincingly and interestingly articulate and defend. Writing practice essays can be also be a good idea -- although, after a few, writing detailed plans (which takes less time) might suffice.
In sum, however you do it, the point is: don't merely lie on the sofa casting an eye over notes. That can be good in the final stage of revision, e.g. the evening before an exam, when you can look over the products of your engagement with the topics. But, at an earlier stage, it's important to do something more active. Simply looking over notes can impart an illusory feeling of understanding. What will produce better understanding and tighter recollection is thinking the issues through afresh, really grappling with them, and (since this is hard) that is something you need to force yourself to do.
It also takes time, and there simply won't be enough time to so as much of this as you'll feel you'll need. Everyone feels this; just do what you can do.
3. EXAM ADVICE
As for how to approach the exam itself, see Adam Rieger's pointers on the department site. Since exam answers are simply essays (albeit usually less polished than coursework essays) it might be worth glancing at some essay-writing advice here and here.
4. GET ON WITH IT!
Don't spend all your time reading advice like this. Once you've got a schedule, take yourself to the library or wherever you work best, and get on with it!
Best of luck!