For me the committee work is done over the course of a few months and although there is some report back and ongoing training it is at a distance. Therefore I try and work in a conversation up front about what success is going to look like to the groups. Have them define what this means, and to be somewhat specific. For example designing smart goals is one option.
Then I work in some check points to see how things are going to date, where they are heading to, what challenges they have overcome, and what challenges are they currently facing.
Committee group work is a challenge, but when they do depend on each other and realize the strengths of their own as well as the other members it is pretty incredible to watch take shape.