Lynn Gaertner-Johnson has a great post on “How to Scare Away Customers.”  The same would apply to scaring away clients.  She quotes this message that a sales representative (yes, this person was trying to sell something) sent to a friend: 

thank you for the rapid response I am grateful for the follow up. as far as information, I sending you an up coming schedule of class's we are offering but let me tell you this, I would like to purpose a special offer of 15% off for all your employee's, plus multi enrollment discounts and periodic specials like buy 2 get one free on select class's. thank you for your time should you need more information please let me know. I look forward to doing some business with you.

It’s easy to feel a little sanctimonious when reading that appalling missive.  But it should be a good reminder that the things we write say a lot about us and our work.