SOLID : Single responsibility, Open-closed, Liskov substitution, Interface segregation and Dependency inversion
Create a system that is easy to maintain and extend over a time to time.
DRY : Don't Repeat Yourself
Develop a functionalities that need not to change but can be extend the functionalists.
KISS : Keep It Simple Stupid
Coding standard must be maintain and approach do simple, so that every developer must be able to understand at one glance.
UX : User Experience