Start by learning the fundamentals of both biology and chemistry (specially topics like cell biology, body systems, organic & inorganic equations). Once you do that, go through videos, charts and 3D models that cover all three topics. This will reinforce the fundamentals.

There are two books I have used, and recommend, for those studying these subjects:

1) Ross Anatomy and Physiology

2) Ace Biochemistry by Dr. Holden Hemsworth

Both are great for solidifying your understanding of anatomy, physiology & biochemistry and will also help you deal with advanced topics easily.

Best wishes. Thank you.