I ran across this extensive article about Writing Cards...Here's an excerpt:
WHAT GREETING CARD COMPANIES ARE LOOKING FOR While the greeting card industry is not stagnant, and new ideas and trends are frequently being developed, the three basic card categories remain the same -- traditional, studio (or contemporary) and alternative.
When publishing a line of greeting cards, in any category, a company must cater to the people who are most likely to buy and send cards. In most cases, that means women between the ages of 18 and 50. So the majority of companies are looking for cards that target issues these women care about; relationships, success, religion, money, health, and so on.
Some of today's best selling cards are non-traditional cards commemorating new jobs, promotions, and salary raises. Other top selling alternative cards deal with relationships, even the break-up of marriages. Still another significant line of alternative cards is aimed at people who have experienced, or are experiencing, drug and alcohol addictions ...Article continued on their website.