What are some practical ways that I can improve my english/ writing skills?

Hi, I am going to school to be an english teacher. I LOVE literature and writing and I want to get a lot better at my reading comprehenshin, spelling, expand my vocabulary, punctuation, and better understand word relationships. What are some practical ways that I can do this over the summer on my own? I have journaled for the past 10 years so maybe there are ways I can hone that in to make it better writing rather than just my ramblings? or reading classic literature? (I'm open to book suggestions) I do have some time but not tons. What are your best tips?