I used to get a few books on the topic and skim between them and flick between the books (in large time chunks - hours or days) and practice things (like C). I

I used to get a few books on the topic and skim between them and flick between the books (in large time chunks - hours or days) and practice things (like C). I have found myself just watching videos now, there seems to be a video or two on everything, made by the experts in the fields. Watching one from Udemy right now - $10 (wait for them on special), they mightn't have the very technical details but enough to get you started so you can find the details out. I remember first watching Gilbert Strang's videos on linear algebra and thinking back to my days of sitting in lecture theatres watching my lecturer teach the same content. I became very envious of "kids these days" :-).