Your blog should include promotional posts and informational posts to keep the interest of your readers intact. People will lose interest if you’re always promotional. But, you can still link to products you mention in educational posts.
To your Success!
Stephen 
I struggled to find an affordable, reliable tool to build and manipulate pdf documents. These ubiquitous documents are so valuable for sharing information, creating brochures and building catalogues of products.
I use SODA and have negotiated a discount for my clients here.