Work problems, not pages
Chemistry rewards practice over re-reading. Close the book and solve the question first — check the worked solution only after you are stuck.
Draw every mechanism
In organic chemistry, redraw the arrows by hand each time. Recognising a mechanism is not the same as being able to produce it under exam pressure.
Keep a mistakes notebook
Write down each question you got wrong and why. Reviewing that list before a test is worth more than re-reading a whole chapter.
Learn the units early
Most lost marks in calculations are unit errors, not concept errors. Write units at every step and the arithmetic checks itself.
Space it out
Four short sessions across a week beat one long session the night before. Revisit a topic a day later, then a week later.
Explain it out loud
Say the answer as if teaching a classmate. The moment you hesitate is exactly the gap to go back and close.