Having someone outside the business or team can be a huge benefit. Not being immersed in your environment I am can see things differently and ask those seemingly ‘silly’ or obvious questions your team members may never think to ask.
These questions can often assist you and your team in getting clarity by explaining it. Another benefit is having a neutral person managing the brainstorming session. It allows everyone to focus on the issue or idea rather than trying to deal with possible internal politics or having to manage the session.
Get a clear picture of what you are want. Create a plan of action and set core outcomes with achievable dates that you and the team can work towards.
This not only reduces stress but also helps in creating a positive team spirit. A clear sense of all pulling together in fulfilling the plan.