Structured data21 is code that you can add to your sites' pages to describe your content to search engines, so they can better understand what's on your pages. Search engines can use this understanding to display your content in useful (and eye-catching!) ways in search results. That, in turn, can help you attract just the right kind of customers for your business.

Thick & Unique Content – There is no magic number in terms of word count, and if you have a few pages of content on your site with a handful to a couple hundred words you won’t be falling out of Google’s good graces, but in general recent Panda updates in particular favor longer, unique content. If you have a large number (think thousands) of extremely short (50-200 words of content) pages or lots of duplicated content where nothing changes but the page’s title tag and say a line of text, that could get you in trouble. Look at the entirety of your site: are a large percentage of your pages thin, duplicated and low value? If so, try to identify a way to “thicken” those pages, or check your analytics to see how much traffic they’re getting, and simply exclude them (using a noindex meta tag) from search results to keep from having it appear to Google that you’re trying to flood their index with lots of low value pages in an attempt to have them rank.
If you are just starting out, don’t think you can fool Google about everything all the time. Google has VERY probably seen your tactics before. So, it’s best to keep your plan simple. GET RELEVANT. GET REPUTABLE. Aim for a healthy, satisfying visitor experience. If you are just starting out – you may as well learn how to do it within Google’s Webmaster Guidelines first. Make a decision, early, if you are going to follow Google’s guidelines, or not, and stick to it. Don’t be caught in the middle with an important project. Do not always follow the herd.
An authority website is a site that is trusted by its users, the industry it operates in, other websites and search engines. Traditionally a link from an authority website is very valuable, as it’s seen as a vote of confidence. The more of these you have, and the higher quality content you produce, the more likely your own site will become an authority too.
Having a different description meta tag for each page helps both users and Google, especially in searches where users may bring up multiple pages on your domain (for example, searches using the site: operator). If your site has thousands or even millions of pages, hand-crafting description meta tags probably isn't feasible. In this case, you could automatically generate description meta tags based on each page's content.

QUOTE:  Each piece of duplication in your on-page SEO strategy is ***at best*** wasted opportunity. Worse yet, if you are aggressive with aligning your on page heading, your page title, and your internal + external link anchor text the page becomes more likely to get filtered out of the search results (which is quite common in some aggressive spaces). Aaron Wall, 2009

Use the Keyword Planner to flag any terms on your list that have way too little (or way too much) search volume, and don't help you maintain a healthy mix like we talked about above. But before you delete anything, check out their trend history and projections in Google Trends. You can see whether, say, some low-volume terms might actually be something you should invest in now -- and reap the benefits for later.
If you take money online, in any way, you NEED to have an accessible and satisfying ‘customer service’ type page. Google says, “Contact information and customer service information are extremely important for websites that handle money, such as stores, banks, credit card companies, etc. Users need a way to ask questions or get help when a problem occurs. For shopping websites, we’ll ask you to do some special checks. Look for contact information—including the store’s policies on payment, exchanges, and returns. “ Google urges quality raters to be a ‘detective’ in finding this information about you – so it must be important to them.
You’ll likely compile a lot of keywords. How do you know which to tackle first? It could be a good idea to prioritize high-volume keywords that your competitors are not currently ranking for. On the flip side, you could also see which keywords from your list your competitors are already ranking for and prioritize those. The former is great when you want to take advantage of your competitors’ missed opportunities, while the latter is an aggressive strategy that sets you up to compete for keywords your competitors are already performing well for.
Smartphone - In this document, "mobile" or “mobile devices" refers to smartphones, such as devices running Android, iPhone, or Windows Phone. Mobile browsers are similar to desktop browsers in that they can render a broad set of the HTML5 specification, although their screen size is smaller and in almost all cases their default orientation is vertical.
OBSERVATION – You can have the content and the links – but if your site falls short on even a single user satisfaction signal (even if it is picked up by the algorithm, and not a human reviewer) then your rankings for particular terms could collapse – OR – rankings can be held back – IF Google thinks your organisation, with its resources, or ‘reputation, should be delivering a better user experience to users.

At the moment, I don’t know you, your business, your website, your resources, your competition or your product. Even with all that knowledge, calculating ROI is extremely difficult because ultimately Google decides on who ranks where in its results – sometimes that’s ranking better sites, and sometimes (often) it is ranking sites breaking the rules above yours.

It helps to improve your ranking for certain keywords. If we want this article to rank for the term ’SEO basics’ then we can begin linking to it from other posts using variations of similar anchor text. This tells Google that this post is relevant to people searching for ‘SEO basics’. Some experts recommend varying your anchor text pointing to the same page as Google may see multiple identical uses as ‘suspicious’.
You can more strategically target a specific location by narrowing down your keyword research to specific towns, counties, or states in the Google Keyword Planner, or evaluate "interest by subregion" in Google Trends. Geo-specific research can help make your content more relevant to your target audience. For example, you might find out that in Texas, the preferred term for a large truck is “big rig,” while in New York, “tractor trailer” is the preferred terminology.

Basically, SEO keyword research should be an ongoing and ever-evolving part of your job as a marketer. Old keywords need to be reevaluated periodically, and high-volume, competitive keywords (or “head” keywords, as opposed to long-tailed keywords) can often be usefully replaced or augmented with longer, more specific phrases designed not to bring in just any visitor but exactly the right visitors. (Who visits your site – particularly if they’re people who are actively looking for your services – is at least as important as how many people visit.)

A breadcrumb is a row of internal links at the top or bottom of the page that allows visitors to quickly navigate back to a previous section or the root page. Many breadcrumbs have the most general page (usually the root page) as the first, leftmost link and list the more specific sections out to the right. We recommend using breadcrumb structured data markup28 when showing breadcrumbs.

QUOTE: “The average duration metric for the particular group of resources can be a statistical measure computed from a data set of measurements of a length of time that elapses between a time that a given user clicks on a search result included in a search results web page that identifies a resource in the particular group of resources and a time that the given user navigates back to the search results web page. …Thus, the user experience can be improved because search results higher in the presentation order will better match the user’s informational needs.” High Quality Search Results based on Repeat Clicks and Visit Duration

QUOTE: “Medium pages achieve their purpose and have neither high nor low expertise, authoritativeness, and trustworthiness. However, Medium pages lack the characteristics that would support a higher quality rating. Occasionally, you will find a page with a mix of high and low quality characteristics. In those cases, the best page quality rating may be Medium.” Google Quality Evaluator Guidelines, 2017
In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[22] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.
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.
QUOTE: “Search engine optimization is often about making small modifications to parts of your website. When viewed individually, these changes might seem like incremental improvements, but when combined with other optimizations, they could have a noticeable impact on your site’s user experience and performance in organic search results.” Google Starter Guide, 2008
How you mark up your images can impact not only the way that search engines perceive your page, but also how much search traffic from image search your site generates. An alt attribute is an HTML element that allows you to provide alternative information for an image if a user can’t view it. Your images may break over time (files get deleted, users have difficulty connecting to your site, etc.) so having a useful description of the image can be helpful from an overall usability perspective. This also gives you another opportunity – outside of your content – to help search engines understand what your page is about.
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.
So what are the rules of thumb here? First and foremost, it’s very important that your content is easy to read. Of course, you should use your keywords in your text, but don’t stuff your keywords in almost every sentence. In general, if 1 or 2% of all words of your copy, is your keyword, then you’re not overdoing it. Make sure your keywords are well-distributed throughout your text. Don’t put all your keywords in the first paragraph thinking you’re done with that part of the optimization. Naturally spread the keywords throughout your page or post. Use your keywords in a subheading or a couple of subheadings, depending on the length of your page or post. And use the keyword in your page title, first paragraph and your meta description. You can find all of these recommendations in the SEO analysis of Yoast SEO.

Submit website to directories (limited use). Professional search marketers don’t sub­mit the URL to the major search engines, but it’s possible to do so. A better and faster way is to get links back to your site naturally. Links get your site indexed by the search engines. However, you should submit your URL to directories such as Yahoo! (paid), (paid) and DMOZ (free). Some may choose to include AdSense ( scripts on a new site to get their Google Media bot to visit. It will likely get your pages indexed quickly.