There will always be mistakes. It is both how often they happen and how you recover from those mistakes that decides whether you are just occupying a desk or whether you are a client services rep worth your salt.
You promised the client designs today. It is 5:30pm, and the designer has gone home, promising that first thing tomorrow the designs will be done. Do you:
A)Send the designs tomorrow, hoping the client won’t notice they are a day late
B)Send the designs tomorrow, apologizing for being late
C)Contact the client today, apologizing that the designs will be late, taking responsibility for screwing up and not defend yourself with excuses
“C” is what I call the No Excuses Ethos. The idea that It Is All My Fault, whether I was there or not, whether it was my responsibility or not. Part of this is establishing with the client that you are totally responsible for everything. Now, this means that your manager has to buy this concept of the client services rep as being a truly responsible person. If you have their support, then you can make the client promises. Which is why you will eventually make a mistake, because you will overpromise (or underdeliver) given that you are not in full control of everything you are promising.
“The files didn’t get sent because the designer was out sick” is never never never acceptable. If it is acceptable to your boss, then quit. If it is acceptable to clients, then fire them. Most importantly, if it is acceptable to you, then reading my blog is a waste of time, because you are not capable of reform.
No excuses. Ever. Even if there are really good ones. The exception I might make is for natural disasters (like Ranier erupting) or people dying. Unless you can say “The files didn’t get sent because the boss died,” then you had better be taking responsibility for the results of your company’s work.
If you aren’t comfortable with that, then get out of client services.