Structured data21 is code that you can add to your sites' pages to describe your content to search engines, so they can better understand what's on your pages. Search engines can use this understanding to display your content in useful (and eye-catching!) ways in search results. That, in turn, can help you attract just the right kind of customers for your business.
The first relates to internal link structure. I’ve made the mistake you say you’ve seen so often. I have a primary keyword and have used that keyword in the main navigation, linked to a page optimized for that keyword. But I’ve also got a bunch of contextual links in posts pointing to that page, usually with the keyword in the anchor text. I now understand that those internal links aren’t helping much, at least from an SEO perspective. Am I better to remove that keyword and direct link from the menu and simply link the page from multiple posts and pages within the site. Or will I get better results leaving it in the main menu and changing the contextual links in the posts to point to a related page with a different keyword?
Robots.txt is not an appropriate or effective way of blocking sensitive or confidential material. It only instructs well-behaved crawlers that the pages are not for them, but it does not prevent your server from delivering those pages to a browser that requests them. One reason is that search engines could still reference the URLs you block (showing just the URL, no title or snippet) if there happen to be links to those URLs somewhere on the Internet (like referrer logs). Also, non-compliant or rogue search engines that don't acknowledge the Robots Exclusion Standard could disobey the instructions of your robots.txt. Finally, a curious user could examine the directories or subdirectories in your robots.txt file and guess the URL of the content that you don't want seen.
I find it interesting that you talked about nutrition supplements for athletes. I am very close to launching such a product for enhancing aerobic exercise performance in women (ie. improved times in a 3 mile run).. The product contains no stimulants or exotic herbs. In fact three of the five ingredients are well known minerals, but in forms not found in most multi-vitamin-mineral supplements. The research behind the product comes from me. The credibility behind the research is that I am a professor of human nutrition with over 100 research papers. Now, the trick will be to use my connections and credibility in a business savvy way.

Great post. I know most of the stuff experienced people read and think “I know that already”… but actually lots of things we tend to forget even though we know them. So its always good to read those. What I liked most was the broken link solution. Not only to create a substitute for the broken link but actually going beyond that. I know some people do this as SEO technique but its actually also useful for the internet as you repair those broken links that others find somewhere else.