Search engine optimization is pretty much based on getting your keywords top ranking in order to increase the visibility of your site. So trying do rank a given keyword without the very element which is central to your overall strategy it's like trying to run a car that operates on gas without gas.
According to me:
Backlinking is most important
SEO is more important
SMO is important
Submission of latest Sitemap on search engines are also important on periodic basis.
I am not an expert. I am talking by personal experience.