to avoid throwing link equity away, you might create HIGH-LEVEL IN-DEPTH TOPIC PAGES on your site and redirect (or use canonical redirects) any related expired content that HAVE INCOMING BACKLINKS, to this topic page (and keep it updated, folding content from old pages, where relevant and there is traffic opportunity, to create TOPIC pages that are focused on the customer e.g. information pages)
QUOTE: “What happens when you have a page with “ten PageRank points” and ten outgoing links, and five of those links are nofollowed? Let’s leave aside the decay factor to focus on the core part of the question. Originally, the five links without nofollow would have flowed two points of PageRank each (in essence, the nofollowed links didn’t count toward the denominator when dividing PageRank by the outdegree of the page). More than a year ago, Google changed how the PageRank flows so that the five links without nofollow would flow one point of PageRank each.” Matt Cutts, Google 2009
QUOTE: “Supplementary Content contributes to a good user experience on the page, but does not directly help the page achieve it purpose. SC is controlled by webmasters and is an important part of the user experience. One common type of SC is navigation links that allow users to visit other parts of the website. Note that in some cases, content behind tabs may be considered part of the SC of the page. Sometimes the easiest way to identify SC is to look for the parts of the page that are not MC or Ads. ” Google Search Quality Evaluator Guidelines 2019
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.
While Google never sells better ranking in our search results, several other search engines combine pay-per-click or pay-for-inclusion results with their regular web search results. Some SEOs will promise to rank you highly in search engines, but place you in the advertising section rather than in the search results. A few SEOs will even change their bid prices in real time to create the illusion that they "control" other search engines and can place themselves in the slot of their choice. This scam doesn't work with Google because our advertising is clearly labeled and separated from our search results, but be sure to ask any SEO you're considering which fees go toward permanent inclusion and which apply toward temporary advertising.
QUOTE: “And we do that across the whole website to kind of figure out where we see the quality of this website. And that’s something that could definitely be affecting your website overall in the search results. So if you really work to make sure that these comments are really high quality content, that they bring value, engagement into your pages, then that’s fantastic. That’s something that I think you should definitely make it so that search engines can pick that up on.” John Mueller, Google 2016
QUOTE: “high quality content is something I’d focus on. I see lots and lots of SEO blogs talking about user experience, which I think is a great thing to focus on as well. Because that essentially kind of focuses on what we are trying to look at as well. We want to rank content that is useful for (Google users) and if your content is really useful for them, then we want to rank it.” John Mueller, Google 2015
If you are using Responsive Web Design, use meta name="viewport" tag to tell the browser how to adjust the content. If you use Dynamic Serving, use the Vary HTTP header to signal your changes depending on the user-agent. If you are using separate URLs, signal the relationship between two URLs by tag with rel="canonical" and rel="alternate" elements.
SEM is better for testing than SEO. Because you can immediately turn SEM paid ads off and on, it’s a great strategy for testing. You can quickly revise your ad copy, target new audiences, and change landing page content to test your new tactics. This flexibility allows you to see differences in your strategies immediately. You cannot accomplish this through SEO, as it would take too much time to make changes and monitor differences in results.
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.
So: how to proceed? On the one hand, SEO best practices recommend that you include relevant keywords in a number of high-attention areas on your site, everywhere from the titles and body text of your pages to your URLs to your meta tags to your image file names. On the other hand, successfully optimized websites tend to have thousands or even millions of keywords. You can't very well craft a single, unique page for every one of your keywords; at the same time, you can't try to cram everything onto a handful of pages with keyword stuffing and expect to rank for every individual keyword. It just doesn't work that way.
Creating high quality content takes a significant amount of at least one of the following: time, effort, expertise, and talent/skill. Content should be factually accurate, clearly written, and comprehensive. So, for example, if you describe your page as a recipe, provide a complete recipe that is easy to follow, rather than just a set of ingredients or a basic description of the dish.
QUOTE: “alt attribute should be used to describe the image. So if you have an image of a big blue pineapple chair you should use the alt tag that best describes it, which is alt=”big blue pineapple chair.” title attribute should be used when the image is a hyperlink to a specific page. The title attribute should contain information about what will happen when you click on the image. For example, if the image will get larger, it should read something like, title=”View a larger version of the big blue pineapple chair image.” John Mueller, Google 2008
If you link out to irrelevant sites, Google may ignore the page, too – but again, it depends on the site in question. Who you link to, or HOW you link to, REALLY DOES MATTER – I expect Google to use your linking practices as a potential means by which to classify your site. Affiliate sites, for example, don’t do well in Google these days without some good quality backlinks and higher quality pages.
Ask for a technical and search audit for your site to learn what they think needs to be done, why, and what the expected outcome should be. You'll probably have to pay for this. You will probably have to give them read-only access to your site on Search Console. (At this stage, don't grant them write access.) Your prospective SEO should be able to give you realistic estimates of improvement, and an estimate of the work involved. If they guarantee you that their changes will give you first place in search results, find someone else.