Short answer: Make short notes from NCERT while reading, revise them on a fixed schedule and test yourself on diagrams and tables.
Notes while reading
Write one-page chapter summaries with keywords, tables and labelled diagrams as you finish each chapter.
Spaced revision
Revise each chapter after a day, a week and a month. Short, frequent revision beats long, rare sessions.
Self-test
Cover your notes and recall the diagrams and tables from memory, then check what you missed.
Frequently asked questions
How long should biology notes be?
Short enough to revise quickly, usually a page or two per chapter.
Should I make notes or buy them?
Your own notes aid memory more; bought notes can supplement.