Before beginning the ideation processs you should agree on ‘ground rules’ with your participants to create a safe and supporting environment. IDEO’s Design Kit provides some good advice on setting the right tone ahead of brainstorming activities.

Object Brainstorming is a non-threatening, abstract and contextually adaptable warm-up exercise, using tangible objects to help externalise the thought process involved in ideation. It involves bringing one or more functional objects to a workshop and asking participants to explore them and to reimagine them as something different, or to use them as inspiration for inventing something new.

Wallet Project is a useful exercise for introducing the concept of user-centred design. It enables participants to practice the process, get the feel of a design approach and gain some shared vocabulary. Stanford University’s D.School provide a worksheet and facilitator guide to get you started. They also provide a video describing the exercise: