Brainstorming
Brainstorming is a group problem-solving method that involves the spontaneous contribution of creative ideas and solutions.
Nominal group technique
in which you ask for as many ideas and solutions as possible, and then rank the concepts to help guide the requirements development
Affinity diagram creations
affinity diagrams cluster ideas into similar groups for further analysis
Mind mapping
Mind mapping consolidates ideas created through individual brainstorming sessions into a single map to reflect commonalities and differences in understanding and to generate new ideas.