The home page of your site is usually a good place to start. It typically holds a wide array of information about your product or service and will lead the website visitor to where they want to go. However, if you have other informative pages on your site that you think would be more helpful, you may want to choose one of those pages in addition to, or instead of, the home page.
For our client: We rolled out a successful implementation of rel="author" for the three in-house content writers the company had. The client had over 300+ articles made by these content writers over the years and it was possible to implement rel="author" for all the aged articles. I advise anyone who has a large section of content to do so as it will only benefit the website. We were also in the process of rolling out further schema markup to the site's course content as it only has a benefit for CTR.
Now, it is not that these sites are not interested in Google users. In fact, they have hired us to help them increase their share. However, they are getting so much traffic from sites like Facebook that it seems there is less urgency about attracting this traffic and less willingness to change the site to meet organic standards. Not long ago, sites would urgently and unquestioningly abide by Google’s standards to court that traffic.