And as a bonus :) I will try describe "my method" of learning languages with using books.
I just find interesting for me books in both languages: target and my native. The level of complexity of the book dosn't matter.
1. on first steps I'm reading some pages of book in my native language and the same pages in target language.
I do not write out the unfamiliar words separately and do not try to learn them especially - they are gradually remembered on their own.
(Of course, you must have sufficient vocabulary for such reading, but vocabulary replenishment is a separate process [*] for me).
The number of pages gradually varies from one (or even half) to a dozen, maybe the whole chapter.
2. Then, from the middle of the book, I'm first reading some pages in the target language and try to understand it, but then I'm reading the same pages in my native language to clarify my understanding.
3. I also download the same or other books in the audio version and listen to them in a similar way to improve my ability to perceive the language by ear.
*For this (vocabulary replenishment), I use Memrise and standard training kits based on a minimal dictionary with a gradual increase in level. Memrise usually offers such courses for all major languages, for example, starting for Russian:
(Of course I use mobile version of Memrise).