If you're studying for finals and want a good study guide, one that pretty much comes out and tells you everything your teacher thinks is important and is most likely to test you on again, check your past exams from the course. They'll be the best study guides you can find.
Tests are teachers' way of measuring what they think is most important. And that's not something most teachers change their minds about later. Unless they tell you otherwise, if it was important enough to put on a test before, it's important enough to ask you about again.
Go back through all your tests first. Deconstruct everything you got wrong and re-do it. Review and remember everything that you did right. Make sure you'd get a 100% if you had to take the test again because there's a good chance it will look familiar when you sit for the final. And if you didn't keep your tests, you've now got a new study skill to try next semester.