I think you can only succeed in the TOEFL exam if you really work hard and enjoy learning about the English language.If you just learn because you need to do the exam it will be very hard for you.You need to become motivated to understand the language,read many texts,listen to many podcasts,songs and movies.This way you will broaden your vocabulary and your grammar and you will succeed.Sometimes you may find you need a teacher to help you,because this exam is not very easy.
Practice makes perfect, you need to test your skills to determine your weaknesses. Begin with the most difficulties you encounter in studying. Sometimes you need to study with someone who mentions the same purpose as you do. Actually Reading expands your knowledge and writing skill, Listening betters your speaking skills. You should study 3 hours daily at least, every week test your skills. The good news here are skills will reach a higher score every phase. After all, you may need a preparation course and making a simulation before the test.