I have written an article about the books and materials you should get prior to your CAE exam – CAE exam books.
Ideally you should prepare well ahead of time before taking your CAE exam. Problem with this exam, however, is that it may take a while before receiving your certificate. I have taken the exam with Cultura Inglesa in Rio de Janeiro and after 6 months the certificate is still not ready. If you need proof of competence within a short timeframe, the TOEFL can be a better option.
Unlike the TOEFL test, your CAE certificate is valid for your entire life. If you don’t need your result ASAP this is therefore an excellent exam for the future. Step one is to acquire the official material described in the above article.
This material gives you a great overview of the format and the answer key gives you the feedback about your current level. Step 2 is to consider a source that can provide you feedback for the speaking and writing sections. Most natural alternative is taking a course.