Kevin Hillstrom is offering some targeting tips in his blog post "E-mail Campaign Management and Data". In this post he talks about how you can improve the performance of your retail email campaign by creating many targeted versions of an email to different customers during one campaign.
To do this you can use attributes such as lifetime purchase history, most recent purchase, clickstream data, user preferences and demographics and lifestyle.
He explains how to do this and which people in your organization you can leverage to do it.
However, he says, "don't expect miracles from targeted email versions. In reality, you have limited data for eighty percent of your e-mail file, so you won't do a great job of targeting to these folks. Among the top twenty percent of your e-mail file, these folks are so productive that many different versions of an e-mail campaign can work. If you can get a fifteen to thirty-five percent improvement in total campaign performance by targeting, you're well on your way to success."
Source: The MineThatData Blog