Hey Ted, thanks for the great questions! The peak times refer to your particular time zone, if you are targeting an audience that resides in the same zone as you. You can also use tools to find out when most of your audience is online. For example, Facebook has this built into their Page Insights. For Twitter, you can use https://followerwonk.com/. Many social posting tools also offer this functionality.
Provide full functionality on all devices. Mobile users expect the same functionality - such as commenting and check-out - and content on mobile as well as on all other devices that your website supports. In addition to textual content, make sure that all important images and videos are embedded and accessible on mobile devices. For search engines, provide all structured data and other metadata - such as titles, descriptions, link-elements, and other meta-tags - on all versions of the pages.
Brian, great post as always! Question: Do you consider authority sites (industry portals) a form of “influencer marketing?” e.g. guest blogging, etc? In some niches there are not so many individuals who are influencers (outside of journalists) but there are sites that those in the industry respect. I am in the digital video space and for me one site is actually a magazine that is building a very strong digital presence. Thanks, keep up the good work!