For me I feel that there are 4 parts to study:
-MCQ
-Structured Question
-Structured Essay
-Practical/SPA
And each way of studying is different.
MCQ
For MCQ, try exposing yourself to the maximum possibilities of
questions which will come out in exam. Try out different TYS or
assignment book. Do and do until you understand and get correct for
each and every question.
Time management is also very important! One must reach a level when
he sees the question at first sight, and the next moment answer is
pop up in the mind. This will save precious time in the exam and
allow you to double/triple check.
Structured Question
Read the question carefully. Try to recall if you have seen any of
the question in TYS or during your revision. Do they look familiar?
Seriously speaking, Cambridge have run out of ideas already. Those
questions you see in your O exam are probably taken from past year.
Their creativity juice has run out.
It's best to read and understand the content of your text book and
make note for it. Have you heard of the 80/20 Rule? It states that out of the whole
chunk of information you have, 80% are non content words, while the
another 20% is the information that you really need. If you were to
make note, you'll save A LOT of time on your later revision.
Keep doing the Past Year Papers, Prelim papers, Mid Year Paper and
TYS. Where there is a source of question, just do it. Expose
yourself to more question, and it will really help you in
exam.
Do the easier question first. Then revisit back the question again
and ponder for an answer. 
Structured Essay
This is the part where you need to memorize a lot of essay. At what
I have said, Make Key-Point Notes! Key-Point Notes are those notes
with just the key point of the content. Then in your mind, link
these points together to show it's relevancy.
No doubt you'll have to memorize quite a lot for this part. Be
glad, There's only a few essay to study per chapter.
Well, it all boils down to your understand. After memorizing, you
should be able to tell if you can understand the content or
not.
Practical/SPA
Probably the lab are closed now for preparation. Revise the notes
your teacher gave you. Also read up your textbook for more
information. Remember Biology practical is one of the most easier
component out of the four.
You must be able to do tests. Like Food Test which consist of four
test. You MUST follow the
instructions . If you missed any steps or do anything
wrongly, the overall result will be different. Usually this will
apply to Plants, where they'll ask you to do something to it.
Drawing. Try practice drawing all the fruits LS and TS. You must
know where is the line of axis(growth direction). You'll be also
required to draw things which you'll never draw before. Weird stuff
can range from ginger to longgag, from chilli to mangosteen. Aww..
Drawing will be an unfair advantage to art students 
Your drawing lines must be clear and concise. No shading! Don't add
3-D effects
