My wiki titled 'englishing' (go to wiki) is primarily for use by students preparing for the Cambridge Advanced English exam. 'englishing' already contains one student-produced word formation reference sheet which I reviewed and edited. After teaching Cambridge preparation classes for six years or so, I've come to the conclusion that building an extensive vocabulary is a key to success on the exam.
How do you build a vocabulary that will be useful? Read, read, and read from a variety of sources. English is everywhere if you pay attention (especially if you're living in an English-speaking country). It's along the highway in the form of billboards and signs; in/on buildings (restaurants, bathrooms, gas stations); on TV commercials; in American/British movies, and, of course, in books, magazines, and newspapers. Usually or often from context, you can figure out the meanings of words and expressions. In this way, you develop a passive understanding of lots of vocabulary.
However, for writing and for speaking, you need more than a passive understanding of vocabulary, don't you? This is where it gets tough. No matter how many times I've taught the CAE, I am always baffled by the difficulty students have in learning and remembering the noun/adjective/verb/adverb forms of common words. The majority of students hate Part Four of the English in Use paper. USING and REVIEWING the words do make the forms stick. Remember to record words and expressions on those index cards or flip cards on a ring (see for an example). You can carry them around everywhere.
When I was a student at UCLA eons ago, I had an American friend who got a Fulbright scholarship to study in Brazil. He was fluent in Spanish as a second language, but he had to demonstrate skill in Portuguese, which he had studied for only a few months before his interview for the Fulbright. Every time I saw him, he had index cards in Portuguese in his hands. It worked! It works!
Good luck on preparing for your CAE, and start enjoying learning vocabulary today!