Have a purpose before you get together. The group should not be trying to develop terms of reference for periodic meeting from a completely blank slate after they’ve met. Groups should have a purpose that is separate and distinct from other groups - you don’t want to be discussing the same issues over and over again in different forums.

Set an agenda, and stick to it. Be as specific as possible on the agenda, it helps define the purpose of this specific meeting. Where possible ask people to submit presentations and reports in advance. Circulate the agenda ahead of the meeting with enough time that participants can come prepared to discuss the specific topics. During the meeting avoid letting discussions drift to issues the group isn’t able to address unless they directly affect the ability of this group to function (and then assign to someone, and move on).

Have the right number of people involved. Involving more people is good for information sharing meetings where status updates, presentations and reports are made to keep others informed. Fewer people should be invited to working meetings at which decisions are to be made. Avoid having $1000 meetings to solve $10 problems.