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
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 have a commenting system (like Drupal, Joomla or WordPress) that allows for search engine friendly links (commonly called dofollow links) from your blog or site, you will probably, eventually be the target of lots of spam, be complicated in tiered link schemes and potentially fall foul of Google’s webmaster guidelines on using the attribute in certain situations.
And so on and so on. The point of this step isn't to come up with your final list of keyword phrases. You just want to end up with a brain dump of phrases you think potential customers might use to search for content related to that particular topic bucket. We'll narrow the lists down later in the process so you don't have something too unwieldy. Once you have your final list, there are several data-driven tools available to you for finding out which keywords you're most likely to rank well for. 
QUOTE: “Some Low-quality pages have adequate MC (main content on the page) present, but it is difficult to use the MC due to disruptive, highly distracting, or misleading Ads/SC. Misleading titles can result in a very poor user experience when users click a link only to find that the page does not match their expectations.” Google Search Quality Evaluator Guidelines 2015
Off-page SEO builds a website’s reputation and authority by connecting it to other high-quality websites. Off-page SEO techniques include: link building (acquiring high-quality backlinks) from other websites and managing local listings and directory profiles. When many websites link to a brand’s website, it shows search engines that the brand’s website is trustworthy, reliable, and reputable, which increases its search rankings.
QUOTE: “What makes a page spammy?: “Hidden text or links – may be exposed by selecting all page text and scrolling to the bottom (all text is highlighted), disabling CSS/Javascript, or viewing source code. Sneaky redirects – redirecting through several URLs, rotating destination domains cloaking with JavaScript redirects and 100% frame. Keyword stuffing – no percentage or keyword density given; this is up to the rater. PPC ads that only serve to make money, not help users. Copied/scraped content and PPC ads. Feeds with PPC ads. Doorway pages – multiple landing pages that all direct user to the same destination. Templates and other computer-generated pages mass-produced, marked by copied content and/or slight keyword variations. Copied message boards with no other page content. Fake search pages with PPC ads. Fake blogs with PPC ads, identified by copied/scraped or nonsensical spun content. Thin affiliate sites that only exist to make money, identified by checkout on a different domain, image properties showing origination at another URL, lack of original content, different WhoIs registrants of the two domains in question. Pure PPC pages with little to no content. Parked domains” Miranda Miller, SEW, 2011
One common scam is the creation of "shadow" domains that funnel users to a site by using deceptive redirects. These shadow domains often will be owned by the SEO who claims to be working on a client's behalf. However, if the relationship sours, the SEO may point the domain to a different site, or even to a competitor's domain. If that happens, the client has paid to develop a competing site owned entirely by the SEO.