1. To master the basic theory of electronic circuits, you must read the most basic books, such as analog electronic circuits and digital electronic circuits.
2. Then accumulate more basic circuits. In the future, designing a large-scale circuit system will be as simple as building blocks.
You can refer to this article "Designing Gesture Control led Lights: After mastering the basic circuit, designing the circuit is building blocks".
3. Start using an EDA software, such as Altium Designer, and do it again according to the mature circuit, from schematic diagram to PCB, and finally make the object.