Building backlink authority for SEO-powered indie projects

Hey all,
I'm currently building a project called PrefabList that will require me to build strong SEO traffic to leverage into revenue.

I've started building SEO-optimized landing pages, but I'm struggling with the backlink building part.

My question has two parts:
• What are the "low hanging fruit" places I can get do-follow links?
• How do you think about more advanced link building for indie projects?

Thanks!