[michielt]

Many years ago I did helpdesk support. Most important thing that I still use: The moment you see that the problem is caused by something out of your control/support tell the customer. After you done that tell the customer you are willing to help a bit but can't make any promises. If you then don't succeed in fixing the problem the customer is still happy because you tried fixing a problem that is not within contract. If you don't tell customer at beginning and you give up by saying, "well this is actually not something for me to help you with" you end the case in a negative emotion for you and the customer.

Other tips: - get somebody else to help you with support - reserve time for support, like an hour a day at a fixed time - don't leave support cases linger in background. something small can/will become a monster