Becoming a master from a newbie at Computer Science and Electronics
I am glad to see your question, because 40 years ago, I was a child who was extremely interested in electronics, radio and computers, and the resources seemed much more limited then. 

I would say, because the field is so broad, it does not matter where you start. Pick something that interests you and go as far as you can with it. My first interest was in building an amplifier to use with a microphone so I could make loud noises (your personal goal does not have to make sense to anyone else) so I read books about transistor amplifiers in hopes of finding a simple design.

My suggeztions are:  


Find an Amateur Radio group and participate  
build some simple kits  
write some simple programs  
use the relevant Stack Exchange sites  
choose some specific goals or projects  
"Nevah, nevah, nevah give up!" (Winston Churchill)  


Don't worry if you don't get to your specific goals - I never built that amplifier - you will learn so much on the way, and become a specialist in something. I eventually became an expert in small transmitting loop antennas, C and data communications. Qapla'!