If you feel your marketing message isn't appropriate for existing customers, consider using a different approach. It's often difficult to know who will see your marketing material. Be careful not to damage any long-term customer relationships.
If you cannot secure an order, then the goal is to get people to proactively respond and say thank you, even though they may not be ready to buy.
Showing without telling—asking questions vs. providing bulleted points—use soft-educational messages rather then hard-core sales messages. Avoid messages such as, "Hey, we do this better than everyone else and you'd be stupid not to do business with us."
Be professional, if you're targeting well-educated consumers with Master's Degrees or PhDs. Use appropriate tone and manner. Don't state the obvious or be condescending or insulting. Avoid textbook approaches such as your product/service 101. This target group doesn't appreciate being spoon fed information, they want the meat and fast!
Always provide customer testimonials or references.
Make it easy for the person to respond, offering phone, fax, e-mail and Website URL.
Create an appropriate offer for your audience. Avoid silly gimmicks, especially when targeting highly educated prospects. Quality information works fine. I've found most people are information hungry.
Incorporate the Web into your campaign. This approach will better educate the prospect and reinforce (digital) relationships, if done correctly.
Ensure the timing is right. Avoid launching on or near holidays. Allow two weeks for delivery of bulk mail. If you're using BRCs (Business Reply Cards), it may take an additional two weeks to get them returned. In all, a month may be needed before you see any results. Ouch. Furthermore, many people may forget they ever responded! I'd suggest using the Web for channeling responses. It's fast, easy and database driven. How about using e-mail next time?