2. Create a user-based tagging system
One thing to do before you start creating and publishing anything is to establish a taxonomy for how modules are going to be tagged within your library of content. This is absolutely necessary for the creation of any kind of automation but also helps your ABM team locate and use what they need.
3. Create your core content
You can take a modular approach to any format, so long as you bake it into the entire planning and production process - particularly for more costly formats, like video ads. This goes back to how you've defined your modules. Within each one, you can also determine whether certain elements can be personalized at the point of distribution - such as dynamically adding in the recipient's name or company, a custom note or video, an image of their website, or references to their key competitors.
For long-form written content, especially key documents like product overviews and thought leadership reports, you can build out the core material as a single project. Write each chapter to work independently, and then tag each module to link it up to your decisioning mechanism or make it available to anyone building content from your module library.