My first stab at prototyping was with an STM32 discovery kit, a couple of breadboards, and a bag of random parts. The best advice I can you give you though is s

My first stab at prototyping was with an STM32 discovery kit, a couple of breadboards, and a bag of random parts. The best advice I can you give you though is start with an idea. Do you want to do sensing, audio, LED art, a tiny game console, a robot? That’ll determine the kinds of hardware you should get and will direct your learning. I can also recommend Making Embedded Systems by Elecia White.