Maths is about understanding and practice.
Sec 3 is the time where you start practicing and understanding,
if you have any doubts, clarify it with your teachers. Many
students have the mentality thinking that they can start to work
hard in Sec 4. That is wrong. You do not have much time to clear
your doubts in sec 4, especially sec 3's work.
Hence, build up your foundation in sec 3. Textbook has a lot of
practice questions, do them and understand fully. Ensure that you
know all concepts and theories, very very important.
~Aldric