What are some ways to do SEO to boost ranking?

Hi SEO members,

I have met and attended a lot of conferences on SEO and most of the SEO experts have mentioned the importance of doing backlinking through Forum Submission, Blog Commenting, PPT Submission, Authored Articles and much more.

I would like to know if these methods are still useful in 2021? Is there anything to add to the existing list of activities that have been mentioned above?