How to get 8.5 band help

I have just gotten back my score and got 7.5. It was my first time ever taking the exam. I have been learning english for about almost a decade now and attended a course specifically for ielts about 5 years ago. Considering i have a good background I took the ielts after just taking couple of mock test as preparation.

But i’m aiming to get at least 8.5 before September. Do you guys have any suggestions on how i can prepare for it? Resources or tips, etc. This band score is needed for future work.