How to Build a Solid Internal Link Structure?
Always provide the user with their location on the site (breadcrumbs, page titles) and give them exit links to the homepage or the sitemap. Clean your navigation links from any Javascript that impedes search engine crawlers. Interlink your most important pages (revenue) and trim navigation bulk menus that confuse users. Build the navigation links for your visitors and not over-optimize them for Google.
Stop for a couple of hours and think about what you can do better with your content. Build a keyword map with the pages and maybe design a visual wireframe of the structure; it will help identify your main landing pages, your traffic hubs. You might need to merge pages on the same topic because your stats don't show they have much traction. Make sure you redirect old to new pages to keep traffic and link juice flowing. If you need to build supplementary pages (stats, information, blog posts, guides, etc.) with lots of content, do it without linking to them from the homepage, but inversely, link those pages to the main topic page, interlink them, and focus conversions on your main cluster page.
