Make it work then optimize.

Start from small then expand.

Don't hesitate to copy code from others.

Don't just copy, understand it.

Learn various algorithms (Data Structure and Algorithms)

Know what you have to know

You don't need to learn everthing

Lastly, touch some grass.

(DRY) Don't Repeat Yourself

(SOLID) Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregationn, Dependency Inversion

(KISS) Keep It Simple, Stupid

(YAGNI) You Aren't Gonna Need It

Aim for cleaner code

Utilize programming patterns (Creational, Structural, Behavioural)