That completely depends on 1) your current level, for both Math & Verbal, 2) the score you need, 3) when you plan to take the test, 4) the time you realistically have to dedicate to test preparation.
Here are some points to keep in mind:
1) The Verbal sections on the GRE, GMAT, SAT, & ACT have nothing to do with TOEFL, First Certificate, or any other test of English as a foreign language. They are much harder; the vocabulary, sentence constructions, and texts are much more sophisticated. These sections test your verbal reasoning skills.
2) “I haven’t seen or done math in years” is a common comment from candidates planning to take the GRE or GMAT. If you’re just rusty, but you used to be good at and/or liked math when you were in school, it will probably come back more quickly than you think—kind of like getting back on a bicycle. If you did not like it and/or were not good at it, you’ll probably need a little more time.
In either case, what many people find difficult at first is the phrasing of the questions and understanding what exactly the question is asking you to solve or answer. Understanding the questions will get easier as you do more problems.
3) If you have a university or program in mind, find out what range of scores most admitted students receive. You can usually find this information under FAQ (Frequently Asked Questions), NOT under admission requirements.
And remember, this range is not a pass/fail score; some admitted students will have received higher or lower scores. Your test score is just one factor that figures into your application profile.