While that theory is sound (when focused on a single page, when the intent is to deliver utility content to a Google user) using old school SEO techniques on especially a large site spread out across many pages seems to amplify site quality problems, after recent algorithm changes, and so this type of optimisation without keeping an eye on overall site quality is self-defeating in the long run.
Don’t be a website Google won’t rank – What Google classifies your site as – is perhaps the NUMBER 1 Google ranking factor not often talked about – whether it Google determines this algorithmically or eventually, manually. That is – whether it is a MERCHANT, an AFFILIATE, a RESOURCE or DOORWAY PAGE, SPAM, or VITAL to a particular search – what do you think Google thinks about your website? Is your website better than the ones in the top ten of Google now? Or just the same? Ask, why should Google bother ranking your website if it is just the same, rather than why it would not because it is just the same…. how can you make yours different. Better.
Note that Google is pretty good these days at removing any special characters you have in your page title – and I would be wary of trying to make your title or Meta Description STAND OUT using special characters. That is not what Google wants, evidently, and they do give you a further chance to make your search snippet stand out with RICH SNIPPETS and SCHEMA mark-up.
When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
The depth of your articles impresses and amazes me. I love all the specific examples and tool recommendations. You discuss the importance of backlinks. How important is it to use a tool to list you on directories (Yext, Moz Local, Synup or JJUMP)? Will Google penalize you for listing on unimportant directories? Is it better to avoid these tools and get backlinks one at a time and avoid all but a few key directories?
The ranking of your website is partly decided by on-page factors. On-page SEO factors are all those things you can influence from within your actual website. These factors include technical aspects (e.g. the quality of your code and site speed) and content-related aspects, like the structure of your website or the quality of the copy on your website. These are all crucial on-page SEO factors.
LinkResearchTools makes backlink tracking its core mission and provides a wide swath of backlink analysis tools. LinkResearchTools and Majestic provide the best backlink crawling of this bunch. Aside from these two backlink powerhouses, many of the other tools we tested, such as Ahrefs, Moz Pro, Searchmetrics, SEMrush, and SpyFu, also include solid backlink tracking capabilities.

QUOTE: “(Google Panda) measures the quality of a site pretty much by looking at the vast majority of the pages at least. But essentially allows us to take quality of the whole site into account when ranking pages from that particular site and adjust the ranking accordingly for the pages. So essentially, if you want a blunt answer, it will not devalue, it will actually demote. Basically, we figured that site is trying to game our systems, and unfortunately, successfully. So we will adjust the rank. We will push the site back just to make sure that it’s not working anymore.”  Gary Illyes – Search Engine Land

The terms SEO experts often start with are page authority (PA) and domain authority (DA). DA, a concept in fact coined by Moz, is a 100-point scale that predicts how well a website will rank on search engines. PA is the modern umbrella term for what started as Google's original PageRank algorithm, developed by co-founders Larry Page and Sergey Brin. Google still uses PageRank internally but has gradually stopped supporting the increasingly irrelevant metric, which it now rarely updates. PA is the custom metric each SEO vendor now calculates independently to gauge and rate (again, on a scale of 100) the link structure and authoritative strength of an individual page on any given domain. There is an SEO industry debate as to the validity of PA and DA, and how much influence the PageRank algorithm still holds in Google results (more on that in a bit), but outside of Google's own analytics, they're the most widely accepted metrics out there.
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.
Sometimes I think if your titles are spammy, your keywords are spammy, and your meta description is spammy, Google might stop right there – even they probably will want to save bandwidth at some time. Putting a keyword in the description won’t take a crap site to number 1 or raise you 50 spots in a competitive niche – so why optimise for a search engine when you can optimise for a human? – I think that is much more valuable, especially if you are in the mix already – that is – on page one for your keyword.
SEO is the practice of optimizing websites to make them reach a high position in Google’s – or another search engine’s – search results. At Yoast, we believe that holistic SEO is the best way to rank your website because you focus on making every aspect of your site awesome. Don’t use any black-hat SEO tricks, because eventually, this will have negative consequences for your rankings. Instead, practice sustainable SEO, with your user in mind, and you will benefit in the long run.
This is also where you can see Google's ML algorithms at work. Powered by Google Cloud Platform, the way Quick Answers and Featured Snippets are extracted gets increasingly smarter as Google introduces new innovations in deep learning and neural networks. These constantly evolving algorithms are baked into how the search engine surfaces information.
Some page titles do better with a call to action – a call to action which reflects exactly a searcher’s intent (e.g. to learn something, or buy something, or hire something. THINK CAREFULLY before auto-generating keyword phrase footprints across a site using boiler-plating and article spinning techniques. Remember this is your hook in search engines, if Google chooses to use your page title in its search snippet, and there is a lot of competing pages out there in 2019.

When Googlebot crawls a page, it should see the page the same way an average user does15. For optimal rendering and indexing, always allow Googlebot access to the JavaScript, CSS, and image files used by your website. If your site's robots.txt file disallows crawling of these assets, it directly harms how well our algorithms render and index your content. This can result in suboptimal rankings.
Google expects pages to “be edited, reviewed, and updated on a regular basis” especially if they are for important issues like medical information, and states not all pages are held to such standards, but one can expect that Google wants information updated in a reasonable timescale. How reasonable this is, is dependant on the TOPIC and the PURPOSE of the web page RELATIVE to competing pages on the web.
Experience can educate you when a page is high-quality and yet receives no traffic. If the page is thin, but is not manipulative, is indeed ‘unique’ and delivers on a purpose with little obvious detectable reason to mark it down, then you can say it is a high-quality page – just with very little search demand for it. Ignored content is not the same as ‘toxic’ content.
I’ve always thought if you are serious about ranking – do so with ORIGINAL COPY. It’s clear – search engines reward good content it hasn’t found before. It indexes it blisteringly fast, for a start (within a second, if your website isn’t penalised!). So – make sure each of your pages has enough text content you have written specifically for that page – and you won’t need to jump through hoops to get it ranking.
The basics of GOOD SEO hasn’t changed for years – though effectiveness of particular elements has certainly narrowed or changed in type of usefulness – you should still be focusing on building a simple site using VERY simple SEO best practices – don’t sweat the small stuff, while all-the-time paying attention to the important stuff  – add plenty of unique PAGE TITLES and plenty of new ORIGINAL CONTENT. Understand how Google SEES your website. CRAWL it, like Google does, with (for example) Screaming Frog SEO spider, and fix malformed links or things that result in server errors (500), broken links (400+) and unnecessary redirects (300+). Each page you want in Google should serve a 200 OK header message.
Google is a link-based search engine. Google doesn’t need content to rank pages but it needs content to give to users. Google needs to find content and it finds content by following links just like you do when clicking on a link. So you need first to make sure you tell the world about your site so other sites link to yours. Don’t worry about reciprocating to more powerful sites or even real sites – I think this adds to your domain authority – which is better to have than ranking for just a few narrow key terms.
Experience can educate you when a page is high-quality and yet receives no traffic. If the page is thin, but is not manipulative, is indeed ‘unique’ and delivers on a purpose with little obvious detectable reason to mark it down, then you can say it is a high-quality page – just with very little search demand for it. Ignored content is not the same as ‘toxic’ content.

However, if possible, I would like you to expand a bit on your “zombie pages” tip..we run a site where are definitely enough pages to delete (no sessions, no links, probably not even relevant with the main theme of the site, not even important for the architecture of the site)..Nonetheless, I am not very sure what is the best technical decision for these pages…just deleting them from my CMS, redirecting (if there is a relevant alternative) or something else? Unindex them on Search console? what response code they should have? ..
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