Best method for studying is writing little tests for yourself and trying to recall your lectures just like you would do in university/school. Obviously this isn't always possible due to time, so the best method I found for studying is writing down notes on a special theory notebook while I read, highlighting sections and uploading quotes to bookwyrm.

There was a method I learned when I studied History which I haven't tried with theory yet, using reading cards in which you write a synthetic version of the main arguments of a book or section you want to study.

I've been reading Lukacs recently and philosophy not being my strongsuit I've found that listening to lectures or video essays that deal with the subject are great for strengthening what i've already read trough.