A meeting without an agenda wastes time
The number one reason meetings run long is that nobody decided ahead of time what needed to be decided. Working out and sharing the topics and goals before you call the meeting means attendees show up already prepared, and the group can reach conclusions in far less time.
Keep a parking lot for anything off-topic
When an unplanned topic comes up mid-meeting, resist the urge to dive in immediately. Note it in a "parking lot," revisit it if time allows at the end, or schedule it as a follow-up discussion -- this keeps the main agenda from getting derailed.
Frequently Asked Questions
How do I handle it when there are too many agenda items?
Rather than trying to cover everything in one sitting, narrow it down to the three or four highest-priority items and push the rest to a future meeting or a separate discussion -- this is usually far more effective.
What if an unplanned topic comes up during the meeting?
Rather than letting it derail the flow, note it as a parking-lot item to revisit if time allows, or set it up as a separate follow-up discussion.