Are you able to do all of the suggested problems and sample test problems, but then do poorly on the test? If so, then study as described here, and then read the following:
When most people study for a test, they do the suggested problems and sample test problems with their notes, the textbook, and the solutions manual in front of them. When they cannot get a question or get a question wrong, they then read the solutions manual or look at the answers to find out where they went wrong or to find out how a certain question is done, and then conclude that they can now do that question. Once they have completed all questions in this manner, they then conclude that they can do all of the problems and are ready for the test.
The problem with the above approach is that you don't get marks on a test for getting questions wrong and then understanding after why you got them wrong. You don't get marks on a test for reading someone else's solution and understanding it. The test is not a reading comprehension test. You also don't have your textbook, notes, or the answers to consult while writing a test. But this is all that you have practiced doing! The only thing that you can conclude after studying in the above manner is that you are good at getting questions wrong, and then understanding after why you got them wrong, and you are good at reading someone else's solution and understanding what they did, but only if you have the notes, textbook, and answers to consult, and only if you don't have the pressure of a time limit. What you need to do is be able to produce the reasoning that produced the solution that you read and understood. You also need to have the technical skill to carry out the algebraic manipulations required to get a question right once you have produced the reasoning that tells you how to proceed with the solution. And you need to be able to do all of this under test conditions!
So here is what you should do. Do all of the suggested problems in the above manner. It is a good start. Then when you feel that you are ready for the test, pick 20 questions randomly from the practice test (assuming that the test consists of 20 questions), and get a timer and set it for 75 minutes (assuming that the test is 75 minutes). Then sit at an empty desk with only the questions and a pen and pencil and start the stopwatch. When the time is up, mark the test. For each question that you got wrong, find 3 or 4 similar problems in the textbook and do them. Do NOT simply find the questions that you got wrong, find out where you went wrong, and then conclude that you can do all of the questions, or that you are now ready for the test. If you do this then you have not read and understood what I have told you so far!! After doing 3 or 4 similar questions from the book for each of the 20 questions that you got wrong on your practice test you should then repeat the above procedure but with a new 20 randomly selected questions.
Keep doing this until you are happy with your mark. Then you will have a realistic view of the percentage of questions that you were able to get right before the test. Then deduct 5-10% from your mark on the practice test, and this is what you should expect to get on the actual test. The 5-10% reduction is due to the added pressure of real test conditions, rather than simulated test conditions. Therefore, if you want to get 80% on the actual test, you should not consider yourself ready untily you have followed the above procedure and achieved a mark of at least 90% on the 20 randomly selected questions, under the simulated test conditions.
