The best way to learn vocab, in my opinion, involves lots of writing and active thinking. You also shouldn't expect to remember every single bit of vocab you learn. What I do, is, in the months coming up to the exam and throughout the year, make a big list as you go of words you do not know the meaning of. This should fill quite a big, daunting book. Then, when it comes to revision, each morning and afternoon take one page and write it out into one word document, concentrating as you do so. This should not take too long. Then learn the page, focus sing on two or three words at a time. Repeat this, until you have completed the book. When finished, go through the Word document and learn again. You will be surprised at the amount you have retained.