Hello, You can try having one standard and one reference book for a subject. Study only from the standard book and use the reference only when some topic is not clear or unavailable. You can either highlight in the books while studying or jot down the points from a topic after giving a read. You should be able to build the concept from those points and they should be revised regularly. No need to memorize the whole topic just remember the definitions as such and start working out application oriented problems along side.

Best of luck.