There is a web site called Exam English, which offers Free TOEFL practice tests for learners of English.
First, if you need to take the TOEFL iBT or PBT versions, you can learn everything you need to know by going to this web site.
Second, the web site offers reading, listening, structure, and vocabulary practice tests to help you improve your academic English. Particularly, the vocabulary section of the web site gives you the Academic Word List, and even gives you practice to test the mastery of the words. The Academic Word List consists of frequently occurring words that you should learn in order to meaningfully improve your academic English proficiency.
Finally, among other benefits, the web site will give you some important tips to help you perform better when you take the exam. If you are serious about improving your academic English proficiency and want to learn more about the iBT and PBT TOEFL exams, please consider visiting this site: http://www.examenglish.com/TOEFL/index.php