I think you can build high quality backlinks to improve the authority
1. Resource page link building: Where else can you find pages online that exist JUST to link out to excellent resources.
2. Infographics: Not the beast they once were, but when done right, they work like a charm.
3. (Smart) guest posting: Don't give up on this strategy just yet. When done right, you can still get fantastic, niche-relevant links from guest posting.
4.Link bait/content creation*(infographics, great resources, etc.*every new piece is another hook in the sea).
5. Email (a very powerful tool for a link builders arsenal).
6. Expert roundup link building - This is a little cheeky but it works a dream…