News Courtesy of SearchEngineJournal.com:
As important as links and publishing content remain, search engines are growing far more complex than relying on traditional text and document analysis to rank its index.
Instead, we should view SEO as an organic ecosystem, where each small snippet of code directly or indirectly ties into the performance of your website.
Link building to a slow site becomes useless, as is publishing content that gets interrupted by obtrusive interstitials on a mobile device.
Following the best practices is pointless, unless you’re following all of them.
Ryan’s Take 
In another excellent post by Search Engine Journal, they list 5 crucial factors for following the best on-site SEO practices. If you haven’t already, you should click on the source link to get all the details. Each of these factors includes multiple subsections which further explain their importance.
Below I’ve listed my thoughts on each topic as well as rehashing what the folks at SEJ think. Of course, on-site SEO should be your first concern before you plan on any external link building or promotional strategies.
Important On-site SEO Factors
Content
No surprise here. SEJ, even breaks out the cliched content is king. While this is true, it can be akin to building the most beautiful house out in the woods. Just simply creating engaging content does not automatically mean it will be discovered.
The minor points made by SEJ relate to user intent, deep content, and organized content. Basically, if you can structure your pages in such a way that is worded similar to search queries, you’ll get more traffic. The more informative and detailed, the better chance you have of ranking for your targeted keyword.
For example, let’s say your business sells canned cat food. You could write a very technical and boring post about your products. Or, you could write it in the form of an essay with a headline such as “Why wet cat food is better than dry for your cat”. Doing it the latter way will find an audience asking that question. The point is to find the most discussed question regarding your service/product and provide a detailed answer.
User Engagement
How much time are visitors spending on your website? Are they clicking to multiple pages or leaving after the first landing page?
Just because a visitor leaves your website after clicking on a search result, doesn’t necessarily mean it is a bad thing. It could mean they found the information they needed and are satisfied. However, if they return to the search results and click on other links for the same query, that is bad. Defined as pogo sticking, many SEO’s believe that this metric is closely watched by Google and factors heavily into their algorithm.
Ultimately, your posts should have a nice balance between satisfying the query and also leading the visitor to your website’s overall goal. Whether that is to provide a service, sell a product, or even expand on a story. You shouldn’t compromise the integrity of your posts and pages to persuade users to this goal. Doing so might backfire, as it is quite easy to detect a legitimate article vs. one that is too much like a sales pitch.
Technical Structure
This is where having an experienced web design agency is crucial. Maybe you’re an expert in spelling and grammar, but if you’re not applying the proper header, alt, and title tags; Google might not understand how your pages are sectioned.
The technical structure also includes non-visitor related content like sitemaps and .htaccess files. Googlebot is pretty sophisticated but not quite human. It needs help crawling your website to index pages. Cluttering the sitemap with useless accessory pages (hello WordPress!) can use up precious resources. A crawl budget is usually enforced on websites limiting how much content can be indexed in a certain duration. It’s important that it is not wasted on pages like image links and demo content.
Interlinking
Are you using internal links on relevant posts and pages? If not, it’s possible that important content is getting buried within your website. I stress the word relevant. Internal linking shouldn’t be forced or over-done, but if you make a blog post and it touches on a topic from another page, that’s when it is appropriate.
Internal linking tells the search engines that the linked page is still valuable. Furthermore, if visitors are clicking on those links, the user engagement goes up. Compare that to a post that has no internal links and it’s almost like a vote of no confidence.
The popular WordPress plugin, Yoast SEO, includes a tool in their premium version to assist with internal linking. This tool offers suggestions for internal links to similar pages and takes out the guesswork out of the whole process. Also, having a few links sprinkled here and there also helps break up the monotony of text by highlighting an important piece of information.
Mobile Responsivity
Numerous studies show that mobile searches are conducted more than desktop searches. With the popularity and affordability of smartphones these days, that shouldn’t come as a surprise. So if your website isn’t formatted for every device, visitors aren’t going to stick around.
Before responsive websites, a different mobile template was the preferred method for satisfying desktop and mobile users. Sometimes these mobile websites have a different URL (http://m.mysite.com). While this is still a tactic used by designers, responsive websites offer a more simplistic and convienent approach.
Since screen space is limited on a mobile device, CSS can be used to hide certain content that isn’t necessary or important. I often ask myself, is it worth it to show this picture or call-to-action box BEFORE important text? If the answer is no, then a sacrifice is made to hide it or move it towards the end of the page on a mobile device.
