Brainstorm once
Doing a brainstorm starting from your own experience and from the unit workbooks is a good first step because it should help you identify what you know well and what you need to expand.
Expand your knowledge
Your challenge is to recognise that you need to go beyond your own experience to answer the question, and that you will need to do some library and web-based research to bring a fuller answer to the question.
Brainstorm twice
A second brainstorm is probably needed after you have read a few books or articles; you should have noticed that you have expanded your knowledge, and that you are able to identify new ideas and make new connections.