I attended the basic class of Nanjing New Oriental. According to my personal feeling and the teacher's introduction, first look at your vocabulary. It's not enough to pass Band 4. If your vocabulary is not enough, there are two options:

1 recite the words by yourself, and then go to the intensive class.

Learn it by heart from the basic class. The progress is relatively loose and there are many parts of speech.

Of course, I don't know. Maybe your vocabulary is already very large, so I strongly recommend that you take intensive classes. You should know that the so-called "skills" will obviously be said in his/her class, so you'd better choose faster and more effective ones. Practice, just find some questions to do, and you can mix them casually.

I hope my answer can help you!