I won't go by the books rather I would focus on the practical things that really help scale the rate of improvement in your ability to hear, write, speak and understand the language.

Short stories
Contextual conversations
Improving pronunciation
Synonyms Antonyms
Paraphrasing
Summarizing
Effective writing
Impactful speaking
Reading and speed reading
Exchanging dialogues
Deciphering talks, videos, movies, songs, books, poems
Getting a hold on British and American slangs
Being mindful about the spell errors
Careful listening

These are some of the examples which show how I would like to take a dip with you into the world of this beautiful language.