Brainstorming is a tool for generating lots of ideas. Fundamentally it relies on one idea sparking other ideas. This works well in a group. One person may have an idea. That particular idea may not have no value but it could spark an idea in someone else which turns out to be very valuable. Therefore it is very important to capture all of the ideas, share them and not to be critical.
Brainstorming Step by Step:
Define the subject or problem to brainstorm as a creative challenge
Select a varied group of people to participate in the brainstorming to try to ensure you have a variety of ideas to provoke and spark new possibilities
Explain how the brainstorming should work
Write one or two words to capture the idea on a post-it
Conduct a fun dry run to make sure people are enjoying the brainstorming and not worried about the process
Give the team a time limit for creating the initial ideas.
Collect the ideas and group similar ideas together
Share the ideas and ask each person to review the ideas and write down any new ideas that are sparked.
Again collect and group the additional ideas
Capture the ideas so that they can be shared with a wider group and reviewed at any point in the future
The next step is to analyse the ideas. Because this is a critical process this is not part of brainstorming and there are many analytical tools for assessing the ideas.
Brainstorming on your own:
If you don't have a group to brainstorm with then you can use your own ideas to spark new ideas. Essentially you still follow the above steps. But you can use time to give you a new perspective on your older ideas. Given enough time the ideas appear to be like someone else's and you can use them to spark new ideas. The most important thing is to capture the ideas so that you can review them again at a future date. Never throw an idea away. It might provoke a completely new idea for a future problem.