I think that all of those are important. Although my experience has been that typically Chinese people tend to overuse vocabulary. They try to use complicated words, and end up misusing them, but still make very simple mistakes in grammar. It also seems to be very common that the grammar that people struggle with most, is the grammar that is not in their native language. For chinese, that is mainly plurals and tenses. I don't know if this is the case for you - it is just what I have often seen. I see you have used the notebook system here. I suggest you continue to use that.

I think practice is the only way to improve you English. You can choose what you like and practice it,.

you need to write a composition a day and have someone to correct and explain mistakes