Use the Feynman Technique: teach what you learn to someone else to identify knowledge gaps.

Write documentation as if the next person reading it is a violent psychopath who knows where you live.

Use a pointer or your finger to guide your eyes. This can increase reading speed by 25%.

Take brief notes after each chapter. Summarizing helps cement knowledge.

Organize books by color for visual appeal or by genre for practical access.

Rubber Duck Debugging: explain your code line by line to an inanimate object.