The most important way to improve the work group is for everyone, especially the bosses, to listen to each other. This can be done in regular meetings and by written communications. Suggestions for improvements should be implemented when possible.
People work better with praise than criticism. Workers should be commended for their efforts and results. Team members should be encouraged to be positive in their attitudes toward the job and other members of their team.
I would like to add that in my experience, the stage is set by management or leaders on effective group dynamics: no prejudice on ideas or folks, no destructive critism, and real followthru, and delegation of real responsibility