A calendar with 12 cartoons / illustrations is a great way of getting your brand seen regularly. Maybe a single calendar cartoon could be relased each month with brand specific dates and occasions. A monthly online version could work as part of communicating with your customer database.
A series based around 12 Days of Christmas is ideal for a social marketing campaign on Twitter, LinkedIn or Facebook. Alternatively, you could always email via your own customer database.
Maybe a single cartoon of a 12 part series could be released each month.