A PLUMBER in the United States has a 10-point checklist to identify potential plumbing problems, which he takes withhim to every job.
He also takes a DVD outlining how a homeowner can save maintenance costs. Imagine he's been asked to unblock a drain. Before he starts he invites the owner to watch the DVD while he's doing the job. He then checks on all the points on his checklist and will usually comeback with one or two things to suggest be done. In most cases he gets instant additional work.
He's doing his customers a favour by carrying out maintenance while he's there,saving them the cost of a further callout. The DVD works similarly because the owner can often identify a job needing to be done. On top of this, he keeps in touch regularly with his customers by newsletter.
His business is run off its feet.