Important factors of SEO

I can't believe there hasn't been a thread like this - or I probably couldn't find it.

So, in your opinion what are some important factors of SEO?

I'll start off by saying:
Having quality content, good on-page titles, and a good meta description. And also, deep linking to other links on your site. So, just don't build your links to your homepage, try to spread your links around and such.

 

It's all here: http://static.googleusercontent.com.../search-engine-optimization-starter-guide.pdf