Always give yourself enough time between writing your letter and mailing it to let you digest it. Ever get a brilliant idea at 4 in the morning?

Proof, proof, proof! We can’t emphasize this enough. Nothing kills your image like misspellings or wrong phone/fax numbers, addresses, etc.

Make sure you present benefits, not features. Did you make a specific offer and not just announce your existence?

Did you highlight why your client should buy from you rather than your competitor? Does your letter clearly outline what response you want the recipient to take?

Did you consider a P.S. with a bonus for quick response?