Which materials to use in order to BOTH construct the BASES of medical knowledge and prepare for step 1

Hi all!
As a first year medical student I’ve a lot of doubts about which materials to use in order to BOTH construct the BASES of medical knowledge and prepare for step 1.
What material do you recommend for me?
Which Step 1 material go more in deep in the details?
(I found Kaplan lectures and first aid a little superficial (mainly FA)).