Even though your TOEFL preparation should really involve incorporating English usage into your life as much as possible, you will still need to develop a specific study plan to prepare for the exact format of the test. In addition to speaking English often, you will need to go over the types of questions on the test, study strategies for answering them, and practice test questions.
Having a schedule and sticking to it is a major component of test prep success. You certainly have plenty of things going on in your life besides the TOEFL test, so you have to be careful not to get distracted from studying.
Depending on how long you have before you take the TOEFL, you should carve out one or two hours to study between two and four times each week.
If you are studying with a tutor, meet with your tutor once or twice each week and then work on the same skills by yourself once or twice for an hour. If you are studying without a tutor, you should still schedule in advance when you will spend an hour going through your test prep book or course.
Choose solid blocks of time that you have free every week: maybe your Wednesday lunch break and your Sunday evening. After a week or two, the studying will be automatic and you will get into a rhythm.
Combining a schedule of times when you can study in-depth for an hour or more with the goal of using English as much as possible will be the secret to your success.