Any Tips On Complementary Web Pages To Support Our Product Site?

As counter-intuitive as it may sound, the kind of pages you have in mind should be less in your face marketing and more "softly, softly".

Avoid merely regurgitating manufacturer's marketing blurb. There is no substitute for original, targeted content that's not available elsewhere. This type of content should add real informational value to your visitor's on site experience.

You real need to give marketing-speak a body swerve.  These pages need to come across as 'independent' and not solely posted online to help make a sale. Even when that is the actual agenda.

Be subtle, keep the text plain and to the point, without slipping in jargon, buzzwords and marketing-speak that will give the game away. Ultimately, complementary pages, i.e. those that support your core pages, must add extra depth to your site and help it to appear to be more than the sum of its parts.