I see a lot of help is available here for grammar; which is a good thing.
There are some technical (proverbial) rules that must be followed while attempting expansion.

1. Structure of Expansion:

The structure of Expansion itself is very important. So, an expansion must be divided into three parts. First being the Introduction which is also called Opening or Begining. Second is Expansion, which is also known as Main-body or Middling. Third portion is the Conclusion; that is named Closing or Ending as well.

The names I have given here would have informed you very well that what you are required to write in there.

2. Word Limit:

Word limit is the second most important rule that one must follow. I have experienced the difference myself. For opening there should be 50-60 words.
For Main-body there must be around 150-160 words. This way for conclusion one is left with 40-50 words because mostly the required length of Expansion is 250-275 words.

3. Introduction must be very strong with good expression. In the main body two or three examples must be given from the real life or some solid examples from history. When one talks about time one can talk about the fatal result of Napoleon etc. To give example of characteristic one may examplify any suitable personality from History or the living legends etc. Finally the conclusion must re-state with different words the theme of whole expansion.