Many have asked the question "how can I improve"?
Improvements comes from knowing what you did right (and not so right) and resolving in the next attempt to do what you know is right (and not do what you know is not right).
The more you are able to coordinate between knowing (competence) and doing (performance), the greater the mastery you will have over your performance and by extension, your results. In a sense, good results come from good practise. Good practise comes from good understanding. To attain this understanding, it is important to know what you know before you can do what you know. Here is an exercise:
Look at the 2008 GCEN SBQ suggested answers. For each SBQ, I have outlined what I know that I have to do in the answers. They are bulleted in the box preceding each answer.
Now take a look at the suggested answers for the recent Social Studies and History Elective SA2. Study the answers (not for the answers per say) to derive a hypothesis of "knows-and-dos" in the soft copy of the suggested answers. As you do this for the other answer schemes, you will discover that they is a blue-print of "knows-and-dos" which you can apply in all and any SBQs.
This is your homework. You can discuss your proposed findings in DISCUSSION if you need a second opinion.