This is my suggestion. For each module, (e.g. Developing Fuels on the OCR Salters course) take a sheet of A3 paper and, in the centre, stick an A5 version of the syllabus for that topic (depending on the size of the syllabus, this may mean you have to use both sides of the paper). Then do the following:
1) Go through the syllabus point by point, and try to write notes for each syllabus point. Check you've covered the key points by referring to a revision guide or your notes, and amend as appropriate. For syllabus points where you were far less sure, go and learn these properly, using your revision guide, textbook, own notes, etc. and then demonstrate your understanding by adding notes to your revision sheet without any help. Repeat this learning process until you can do this confidently.
2) Then go through your class notes and look for work and tests where you received feedback on things you got wrong or could have done better. Add these points to the relevant syllabus points, perhaps in a different colour.
3) When answering past paper questions and using the mark schemes to check your answers, if there's anything you learn here, add that to the relevant point(s) on the syllabus on your revision sheet. Again, using a different colour might help.
As I see it, there are several advantages to this approach over ploughing through a revision guide or just your class notes from beginning to end.
1) It ensures that you cover everything you need to know and nothing else, since you won't be tested on things not on the syllabus.
2) It allows you to review what you do know and not waste time revising areas of strength.
3) The focus on the syllabus should allow to get into the examiner's head. Remember, the questions that they set directly relate to the syllabus and, in many cases, the syllabus contains the specific answer to a question. For instance, on the Salter's Chemistry specification, there are the steps for determining the concentration of a coloured solution by colorimetry, the similarities and difference between line absorption and emission spectra, and the reasons why clinical trials for drugs are required, to name but a few, which are the direct answers to the typical questions given on the exam papers that relate to these topics. Simply no other answers are required, or, indeed, necessarily accepted. More subtly, there are other cases where a knowledge of the syllabus will help you to appreciate what things a question wants mentioning. An example on the OCR course is in Agriculture and Industry, where the syllabus says that students must recall the physical properties of different types of substances, but in brackets lists solubility in water, melting point and ability to conduct electricity. So if you get a compare and contrast question on the properties of different substances, these would be the properties to go for.
4) It forces you to learn from your mistakes, be that through the course of the year or at the end of revision when doing past papers.
5) You end up summarising a whole unit on one A3 sheet of paper, which is a personalised, paired-down summary that hopefully can be learnt in the time available to you.