Teams is easy to turn on and easy to make a mess of. A little structure up front prevents most of the common complaints.
Teams, not channels, mirror your org chart
Create a team per department or major project, not per topic. Channels within a team should represent ongoing workstreams — spinning up a new team for every small initiative leads to sprawl nobody can navigate.
Decide who can create teams
By default, most tenants let any user create a new team. Left unmanaged, this produces dozens of abandoned teams within a year. Restricting creation to admins, or requiring a naming convention, keeps things navigable.
Standardize channel names early
"General," then a small, consistent set of channels per team (Files, Planning, Client Work — whatever fits your work) makes it far easier for new hires to get oriented.
Archive, don't delete
Completed projects should be archived rather than left active or deleted — archived teams stay searchable without cluttering the active list.
Teams becomes genuinely useful once there's a light structure behind it. Without one, most organizations end up defaulting back to email within a few months.