Depends on the level.
Primary and secondary school levels 
listen to class
attentively, go back home and revise what have been taught. What's
the most important thing is to understand what's been taught, not
to memorize what's been taught. Try to find real life applications
if possible. Otherwise, books you read also helps. If you can
remember some details of that book and it has been covered in the
textbook, it will help you understand the topic taught.
Tertiary (ITE, JC, Poly and Uni) students attend
the tutorials and lectures regularly. Try not to miss anyone of
them. If in doubt, ask. Best to read up more books as you are no
longer being spoon-fed when you are in primary and secondary
school. Understanding is a must, no point memorizing as the
information has no end to it. Pick up the main points, find some
good examples to support it. You need to understand the examples,
so you could explain it well during exams. If not, it's of no
use.
As for lifestyle, find the best time to study. Some people work
best in the morning, while others at night. Have a good break
before you study, eat well and rest well. Before exams, don't burn
midnight oil. Learn whatever is possible during the day and learn
some again on the exam day.
