There are many different brainstorming techniques you can use to come up with new ideas. These include mind-mapping, SWOT analysis, Rapid Ideation, and Brainwriting. Other popular options include Six Thinking Hats and SCAMPER (Substituting, Combining, Adapting, Modifying, Putting to another use, Eliminating, or Reverse).
The best technique to use depends very much on the context of your situation, plus the goals of the brainstorming session. I recommend mixing and matching different techniques to find what works best for you.