Must have add-ons skill as a Mern/Mean Developer :

1. Github or any other
2. 2. Understand deployment cycle ,how build is made from project
3. 3. Write dynamic test cases (User perspective )
4. 4. Get understanding of how version control work
5. 5. Understand one or two cloud services how they work
6. 6. Learn about docker
7. 7. Map out business logic first before start to code