The single most important thing is to make the client happy. If you are making the client happy, as a side effect, they will be happy to open up their business and will give more business to you.
If we ever called VINTAGE number, it would be picked up in less than 2 rings with a friendly voice answering. For any time, there was always somebody to pick up call in 2 rings. No voice mail system, no routing to different departments. VINTAGE treated us like our best friends and providing us best candidate.