High quality content
Link forum
Citation
Broken links
Image links
Infographics
Guest posting
Brand mention
Link placement
Resources
this might help you https://www.onlineofficer.com.au/seo/10-seo-statistics-every-business-owner-should-know/
If you are investing in SEO this has a lot of work to do.
Might as well check your competitors or the 1st-page rankers what are they doing you can implement it also on your site.