1. Define the problem/goal in simple and easy to understand terms, even to someone who does not work with that problem directly (ie: Accounts should understand a marketing problem to be able to suggest ideas)
2. Identify who should be in the meeting. Ideally, team members who are directly affected (possibly experts) should join, but also colleagues who are little to not connected at all to it. This allows for diversity in perspectives and less bias. Go for 3 to 8 people to ensure everyone participates. If you need to include more people, you may consider several rounds with different groups.
3. Prepare the showcase of the problem. Think of what the participants already know about it and what definitions and context you need to provide for them to fully understand the problem.
4. Send out any pre-work that the participants can do ahead of the session.
5. Choose the technique you want to use for the brainstorming for maximum effectiveness. The considerations for this might be: who the participants are, place and time, resources available, how you want to collect the ideas at the end etc.. Be mindful of power dynamics and participant confidence to share ideas and choose a technique that enables everyone to engage.
6. Pick an appropriate facilitator. If not, it could be one of the experts, the project manager who will work on the execution of that solution, or someone very experienced in facilitation. – Set the agenda, venue and send out the invitations.