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.
QUOTE: “They follow the forms you gather data you do so and so and so forth but they don’t get any laws they don’t haven’t found out anything they haven’t got anywhere yet maybe someday they will but it’s not very well developed but what happens is an even more mundane level we get experts on everything that sound like this sort of scientific expert they they’re not scientist is a typewriter and they make up something.”  Richard Feynman, Physicist
It's wonderful to deal with keywords that have 50,000 searches a month, or even 5,000 searches a month, but in reality, these popular search terms only make up a fraction of all searches performed on the web. In fact, keywords with very high search volumes may even indicate ambiguous intent, which, if you target these terms, it could put you at risk for drawing visitors to your site whose goals don't match the content your page provides.
QUOTE: “So it’s not something where we’d say, if your website was previously affected, then it will always be affected. Or if it wasn’t previously affected, it will never be affected.… sometimes we do change the criteria…. category pages…. (I) wouldn’t see that as something where Panda would say, this looks bad.… Ask them the questions from the Panda blog post….. usability, you need to work on.“ John Mueller, Google.
You may not want certain pages of your site crawled because they might not be useful to users if found in a search engine's search results. If you do want to prevent search engines from crawling your pages, Google Search Console has a friendly robots.txt generator to help you create this file. Note that if your site uses subdomains and you wish to have certain pages not crawled on a particular subdomain, you'll have to create a separate robots.txt file for that subdomain. For more information on robots.txt, we suggest this Webmaster Help Center guide on using robots.txt files13.
Yes, you need to build links to your site to acquire more PageRank, or Google ‘juice’ – or what we now call domain authority or trust. Google is a link-based search engine – it does not quite understand ‘good’ or ‘quality’ content – but it does understand ‘popular’ content. It can also usually identify poor, or THIN CONTENT – and it penalises your site for that – or – at least – it takes away the traffic you once had with an algorithm change. Google doesn’t like calling actions the take a ‘penalty’ – it doesn’t look good. They blame your ranking drops on their engineers getting better at identifying quality content or links, or the inverse – low-quality content and unnatural links. If they do take action your site for paid links – they call this a ‘Manual Action’ and you will get notified about it in Webmaster Tools if you sign up.
The errors in technical SEO are often not obvious, and therefore one of the most popular. Mistakes in robots.txt and 404 pages, pagination and canonical URLs, hreflang tags and 301 redirects, http vs https and www vs non www versions: each of them can seriously spoil all efforts to promote the site. One quality SEO website analysis is enough to solve all the main problems in this part forever.

QUOTE: “Returning a code other than 404 or 410 for a non-existent page (or redirecting users to another page, such as the homepage, instead of returning a 404) can be problematic. Firstly, it tells search engines that there’s a real page at that URL. As a result, that URL may be crawled and its content indexed. Because of the time Googlebot spends on non-existent pages, your unique URLs may not be discovered as quickly or visited as frequently and your site’s crawl coverage may be impacted (also, you probably don’t want your site to rank well for the search query” GOOGLE
Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
QUOTE: “The duration performance scores can be used in scoring resources and websites for search operations. The search operations may include scoring resources for search results, prioritizing the indexing of websites, suggesting resources or websites, protecting particular resources or websites from demotions, precluding particular resources or websites from promotions, or other appropriate search operations.” A Panda Patent on Website and Category Visit Durations

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.