Before you begin to learn any design tools or any of the fundamentals of design you have to begin to train yourself to see good design and also be comfortable sketching as you would need this skill for rapid prototyping. These two are very important.
As a designer, you would have to be able to work with a vast amount of creative tools. but your most reliable tool would always be a pen and a paper. So you have to learn to get comfortable sketching out your ideas. I by no means expect you to start drawing portraits and crazy figures but you should be able to use simple lines and shapes to get your ideas into the world fast.
Designers are basically problem solvers.
Your job as a design to apply the tools you have to solve problems. A
global design company, IDEO, have created a system for design thinking
that can be learnt and applied by anyone and everyone.
“Design thinking is a human-centered approach to innovation that
draws from the designer’s toolkit to integrate the needs of people,
the possibilities of technology, and the requirements for business
success.” — Tim Brown, President and CEO of IDEO