Quality content will help you differentiate yourself as an authority to the search engines, they don't like to see when entire paragraphs, even entire webpages are duplicated. It will also help you capture a caring audience that will eventually share some of your work on social media, giving you authority to the search engines that way (which is actually one of the best ways available to increase page rank). A huge part about writing with quality, is writing for your target audience, not for a certain advertisement to show up on a network, and not as if you are trying to make a profit. You have to kind of empathize with their struggles, their feelings, and their concerns, and then you have to give a thought-out opinion or good solution about and to the issues at hand.
The meat and bones of the SEO when it comes to your content should only come afterward. It's a lot easier to write great content when you don't have to constrain yourself with thoughts like "Oh, I need to write exactly for this keyword or I won't be seen!". No, this is not the case. All of the better ways to do SEO in fact have very little to do with your content outside of keywords related to your niche. It's when people like or share your article, blog post, music, or whatever other content you have via social networks and - in the case of webmasters - other websites, that Google really cares about. Google has long known that no formula or algorithm is suitable when it comes to keywords and things controlled by the webmaster to determine how good the content really is, so it is often what other people do for your content that determines its fate. Making sure you follow proper on-site SEO practices and such are just supplementary, but they should also never be neglected. That, and that alone, is the secret to SEO. This is why they say "content is king".
The only problem with this is, sometimes you hit the mark on what people like, sometimes you don't. You just have to keep trying, but once you have your first ten likes, shares, pins, etc. it just gets easier from there.