Social media. The algorithms have truly changed since social media first emerged. Many content websites are community-oriented -- Digg began allowing users to vote which stories make the front page, and YouTube factors views and user ratings into their front page rankings. Therefore, e-commerce stores must establish a strong social media presence on sites like Facebook , Pinterest, Twitter, etc. These social media sites send search engines signals of influence and authority.
Lastly, it's important to remember that paralysis by over-thinking is a real issue some struggle with. There's no pill for it (yet). Predicting perfection is a fool's errand. Get as close as you can within a reasonable timeframe, and prepare for future iteration. If you're traveling through your plan and determine a soft spot at any time, simply pivot. It's many hours of upfront work to get your strategy built, but it's not too hard to tweak as you go.