Although I am not working telephone-based customer technical support anymore, there are a few very important lessons I learned from that time that are still important today.
1. ALWAYS be friendly and accommodating to the person you are being paid to help even if what you want to do to them is going to land you in prison for life.
2. Take time to ask lots of questions so you can get a detailed picture of the situation in your mind, especially if you are confused or unsure of what to do.
3. Offer people options when possible.
4. ALWAYS maintain full control of any situation where YOU are the one being asked for help.
5. The problem's not solved until the user verifies it is solved.
6. Never hang up/ditch/fire/ignore a user without EXPLICIT approval from management.
7. Follow-up NEEDS to be a habit.
8. The problem's not solved until you have considered every contingent situation that may affect the issue or undo your solution.
9. Escalate as soon as you realize that you cannot satisfy the user.
10. OWN the issue from birth to resolution no matter what happens unless management kicks you off the case.
11. Keep your nose clean. At the time you least expect it, a dissatisfied user is going to run their complaints all the way up the flagpole. Your manager will the next-to-last person on the recieving end of a fast-moving pile of dung. If it is found that you varied at all from company policy and procedures, BAM! you're to blame.
12. Thoroughly and accurately brief your colleagues on user issues, either in conversation or through documentation. Otherwise, your customer service may come into question on account of miscommunication.