I have been working on various server side/client side technologies in different implementations from past six years in MNC companies. I become a successful developer by understanding and implementing the following principles in my product development.
A product can be a successful product if we take care each and every element to match with business requirement with best industry standards.

User Interface:

1) Responsive web design.
2) Reusable code
3) Easy and best-fit architecture to spend less on
maintenance
4) Minimal user clicks for achieving an operation.
6) Good looking user interface design

Server side:

1) Scalable architecture.
2) Cloud support
3) Choosing the best architecture to support multiple
Clients.
4) Using best design patterns.
5) Separating business logic from Data access tier.