If you aren't doing this, you should:
1) Stay on Live Chat. If you don't have one, get one. If a node goes down and you don't answer tickets quickly enough your clients WILL come here and to WHT to complain about it. It also cuts down on easily-resolvable support tickets. If you require a paper trail or more clarification, have them submit a detailed ticket about their issue.
2) When something goes wrong, say something about it. If you messed something up out of incompetence, at least lie. The point here is you cannot leave your clients in the dark. They feel much better being given some form of response. An ETA, even if it's continually extended. You might think that too many negative posts on the Announcements page looks bad but it's good to do.
3) Remain professional and type as neatly as you can. Stray away from public forum drama. Don't insult people or attack previous clients, ever. Also, no client wants to see a half-ass reply or poor usage of the English language. If you cannot type professionally think of what that says about your ability to comprehend. Do not get too comfortable with your clients either. You want them to believe you have high standards.
4) Do not be greedy. Refunds are good. If a client has had real bad service with you thus far and they want a refund, give it. It may save you from being another horror story on here or WHT. When you return funds to your clients it shows that you are not a scammer. It makes you appear you are doing better off than you are. People are easily turned away after reading a bad review.
5) Be stable. You want as much uptime as possible. It looks really good. If you're using technology you don't understand, stop. Beta test before implementing something. These guys did this, these guys did not.
6) Remain active. Help your clients out. You're knowledgeable aren't you? Post tutorials. Consider an IRC or a forum. (moderate it!) You want your clients to know there is a community they can turn to for assistance. Not everyone knows how to use Google.
7) Be swift. Monitor your nodes! Watch for abusers. Don't wait until someone has to complain about it. Be swift to answer your tickets as well, but remember to be detailed and read exactly what your client said. Answer all the questions!
Note: I hope my tutorial hasn't offended anyone as it was not meant to. It just highlights some of the things I look for in a provider and stuff I hope other providers start striving to do. I currently do not own any services with any of the providers I used as references in this post.