IELTS is a proficiency test for you to go abroad. Some English training institutions attach great importance to test skills for this kind of training, because the ultimate goal is only to get a good score abroad ~ ~
You are a sophomore now. If you want to improve your English, of course, new concepts are the best, classic textbooks ~ ~
I suggest that you recite all the texts in Book 3 as far as possible, not too long, one text a day, which is very useful for your future reading and writing ability.
Secondly, practice listening. I recommend listening to this. If you have a CD, practice by yourself.
Finally, oral English requires you to find a relatively suitable environment for you. It is best to get to know foreigners. If it is difficult, you can find out if there is an English corner or something.