Creating high-quality long-form content that ranks in the first page will fetch you lots of backlinks.
Guest posting is essential since it can help websites exchange links.
You must outreach to niche-specific websites for backlinking and guest posting.
There are many online niche-specific directories to help you get niche-specific websites and get yours listed as well!
You can check your competitor’s backlink profile using SEO tools and outreach to those websites.