The exam preparation industry is huge business: You can take courses in almost every conceivable major testing system there is to get the place you want in University: Whether it’s undergrad (SATs), postgrad (for example, gmat prep), foreign study (IELTS/TOEFL), or doctoral work. Whatever you need, these days you’ll find someone who’s helping you to pass the exam.
Of course, as a course prep teacher, I have to say that such tests are often taken by students without sufficient background in the knowledge sets they are asked to be tested on. For example, I have had IELTS students approach the IELTS test not recognizing that it is a proficiency test rather than a discrete knowledge test, thereby making it impossible to improve fast without doing some serious amounts of practice.
So before you decide to take a test, determine its nature, its purpose and the kind of knowledge or skill set you’re being tested on. Because you may get disappointing results, if you don’t.