Who exactly is the market for your products and services and what do they like online, on blogs, on Facebook, Twitter, discussion forums etc.?
Use the likes of the Facebook Ad system to figure out the volume of the people you are interested in interacting with and increase that by perhaps 30% for overall Internet numbers.
Themes could be a week long education initiative, a week of special offers/discounts, a week of tips on how to use your products more efficiently etc.
The more you understand about your customer/potential customer the more you can use language they appreciate, market where they spend their time offline and online and design a product that they’ll want.
Digital Marketing allows you to use the same basic message in different online “channels” and with slightly different messaging so it fits the context.
So figure out what people like by past experience or see how they presently interact with their friends on Twitter and Facebook, what content gets them going and see can you provide content like that.
Getting interactions too might be as simple as asking for them.