Passive vs active + relationship building.
Video could play a part.
Ideas:
make a short video for the top 5-10 posts in each category embed in content add to channel
create a short video for each product does not have to be full vsl just describe the book features and benefits
welcome to the site
about the author and the site
pick a topic or category and record a short series could be code examples could be video lecture
thanks and here to help if you have questions
post to social post to youtube add to site