How to increase domain Authority ?

Do some paid Business Listing.

1- Create High Authority Backlink
2- Create Killer Content That's Link Worthy
3- On page SEO Audit
4- Audit Your Site and Remove Bad Links.

Work On Content and create good authority backlinks.

Acquire High-Quality Backlinks from Authority Sites. If you noticed, backlinks play a huge role in calculating domain authority.

Build high quality backlinks

Create Guest posting Dofollow links on Good DA site.
Check here guest post site - https://www.postingera.com

1 - Acquire High-Quality Backlinks from Authority Sites. If you noticed, backlinks play a huge role in calculating domain authority
2 - Create Killer Content That's Link Worthy
3 - Audit Your Site and Remove Bad Links
4 - Improve Your Internal Links
5 - improve On-page Optimization
6 - All Website errors solve

Add Quality Content in your website, remove copy content on your website, remove spam backlink, and remove all error form google webmaster tools.

Acquire High-Quality Backlinks from Authority Sites. If you noticed, backlinks play a huge role in calculating domain authority.

Create Killer Content That's Link Worthy. ...
Audit Your Site and Remove Bad Links. ...
Optimize Your Website Structure and User Experience. ...
Improve Your Internal Links.

while doing bookmarks you should work with High DA sites, most important thing should be Dofollow site

make a worth full backlink to increase DA of website

Obtain Quality Backlinks from Reputable Websites. As you may have seen, backlinks are quite important for determining domain authority.
Make link-worthy, killer content.
Examine Your Website and Discard Unsafe Links.
Improve the user experience and structure of your website.
Make Internal Links Better.

Post Regularly Quality Content and backlinks.

Create High-Quality Backlinks, Improve content quality

Quality Content is always king for google, Instead of quantity focus on Quality backlinks from high DA and PA website if you want to improve Website authority

Create more high quality do-follow links from various platforms. also, work on good and unique content.

High-quality backlinks

Acquire high authority back-links from specific niche-related sites regularly.

work on increase page or get good quality backlink like first you have to think about spam score do-follow or no-follow backlinks and high domain authority website