Some people like to have some time to think in advance, so give a short brief about what your objectives are. This way, they can come prepared with ideas in hand.
During the work session, pose a question and set a short amount of time for everyone to generate ideas on their Post-it® Notes. As people present their thoughts, arrange them on the wall or table. And allow people to add to the mix if one idea sparks another, or a variation on an emerging theme.
At the end of the session, you can further organize the Post-it® Notes and sheets from Post-it® Big Pads and capture them using the Evernote camera in Post-it® Note mode. Auto-tag them or assign meaning to the colors before saving your notes into a shared (or private) Evernote notebook. Between the tags, colors and search capability, it's easy to track them down when you or others are ready to build upon your early ideas.
Think of something later? You can always add to the Evernote notebook whenever inspiration strikes.