I modified my original post to add a fourth element of basic best practices for successful mail & e-mail. Timing is a key element of any marketing communication. It should arrive at a time that is relevant to the customer.
With the holiday season approaching, now is the right time for marketers to focus on things relevant to the giving gifts, whether it is a holiday gift for family or friends, or giving the gift of charity for those less fortunate. Mid-November through late December is not a time to spend limited marketing dollars soliciting customers for low-interest categories such as phone service. To quote Bob Stone, direct marketing guru and writer of Successful Direct Marketing Methods, to the best of my recollection, "Once JCPenny has it's first Christmas sale, little else matters." That sale is typically the second weekend in November. This year, it could even be this coming weekend.
Likewise, a good time to actively market health products and financial services is January and February. Consumers are past the holidays, looking at their waistline and their credit card and bank statements. Many enter a period of self-reflection. This will be a good time to offer savings tools, higher interest rates on savings and lower interest rates on credit cards. In recent years, many banks used the first quarter to roll out acquisitions offers with teaser rates and low promotional balance transfer APRs. (However, the rules changed with Credit Card Accountability, Responsibility and Disclosure Act, so this may not be the case next year.)
If you have a great tool for managing budgets or a dietary supplement to offer, it would be a Fail to mail or e-mail an offer now. Likewise, if you sell gift baskets, it would be a Fail to mail a catalog in January.