Proper membership
Ask three questions when selecting team members: 1) do potential members have expertise in the problem the group must deal with?; 2) do they have political pull that can help the team fulfill their charter?; 3) can they all get along?
Expertise is a sticky issue: if all team members have substantial expertise in the problem area, they may not see the forest for the trees, yet a group of novices can make fundamental mistakes. Based on experience, the amount of expertise required for a group to be effective depends on the purpose of the group. If the purpose is to make incremental, small scale change, weight the group with experts. If the purpose is fundamental, large-scale change (re-engineering), weight the group with "less-than experts."