Create content keeping in mind the reader's standpoint
It should be in the form of an instant article (e.g. facebook instant articles)
for targeted keywords only 2-3max., do not, I repeat don't overdo #hastags
as it does not make any sense and the user will definitely ignore your post, on whichever social media platform it may be.
These days, short video content is becoming more popular among users, e.g on facebook, instagram & twitter, so, create content accordingly.
Running ad campaigns may also be helpful but is often costly but once done correctly chances are your website will receive a traffic boost.
There are other SEO techniques for social media but above ones are more effective.