One of the most important things to make a decision-making process effective is encouraging empathy between the participants. This is a hard thing to cause and is risky in some ways because it involves participants sharing themselves. One of the tools I use is story sharing.
To start story sharing, I break the group up into pairs by counting off. The pairs then share with each other a story from their life that had a powerful impact on them. The pairs then discuss their stories and dig deeper into the impact and importance.