Review personal experience. Review related scientific data and principles. Review applicable technology. Search the library and available literature. These are just a few places to look.
Every problem provides new challenges and opportunities to find new solutions.
The Brainstorming activity is an exercise in creativity. Make no judgements of any ideas during Brainstorming. There are two sides to the brain. One is strong in creativity, the other is strong in judgement and analysis. Lock the Judge in the closet during Brainstorming The wilder the idea the better.