A very effective technique is to include only that content most relevant to the recipient. For example you could include a renewal notice that will be seen only by those up for renewal in the next month. Or you could include different specialized articles for recipients based on whether they are in academics or industry. You can create unlimited options because you have access to the complete power of the information in your membership database.

And of course, you can always personalize messages by merging in a salutation (e.g. "Dear Dr. Smith"), membership status (e.g. "Member since 1997"), or any other information from your membership database.