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.
Paid or sponsored ads usually charge you for a click, while SEO doesn’t require you to pay for impressions or clicks. But do keep in mind that quality SEO isn’t exactly free. Depending on the target market you are in, you will have to invest time and money into getting the desired results. And if you’re not an SEO expert, then you would have to work with a reputable SEO company do it for you.
In the zero-results sets, Google was still willing to show AdWords, which means if we have customer targets, we can use remarketed lists for search advertising (RLSA), or we can run paid ads and still optimize for those. We could also try and claim some of the data that might show up in zero-result SERPs. We don't yet know what that will be after Google rolls it back out, but we'll find out in the future.
Guest blogging purely for inbound links is a flawed strategy because the value of those links are going down. However, guest blogging for traffic is still an incredibly viable strategy. While that inbound link you get at the end of a guest post doesn’t have as much SEO value as it used to, it still has the value of exposing your content to a new audience.
In some contexts, the term SEM is used exclusively to mean pay per click advertising, particularly in the commercial advertising and marketing communities which have a vested interest in this narrow definition. Such usage excludes the wider search marketing community that is engaged in other forms of SEM such as search engine optimization and search retargeting.
Well, yes and no. Sure, you can get hit with an algorithm change or penalty that destroys all your traffic. However, if you have good people who know what they are doing, this is not likely to happen, and if it does, it is easy (in most cases) to get your visits back. Panda and Penguin are another story, but if you get hit by those it is typically not accidental.