How long will each item take?
It is useful for the chair and secretary to look at the agenda before the meeting and work out how long they think each item is going to take. This can really help with the chairing and general smooth running of the meeting.
Try to make sure the important discussions get all the time they need, and the minor issues don't expand to take over the whole meeting. If this looks impossible you need to have fewer items on the agenda, or a longer meeting.