Brainstorming is useful for generating alternatives in many situations, such as
project plan development
risk response planning
scope definition, cause-and-effect analysis
creative problem solving
Brainstorming is a group technique, depending on teamwork and interaction for good results. Gather people who can be expected to have insight into the current situation or problem to develop ideas.
Clearly present the problem statement, and encourage discussion if it is unclear. Post the statement where it will be visible to everyone.