YouTube
AfroTechMods – Excellent tutorials and simpler projects.
GreatScott! – A little step up from AfroTechMods, more projects.
EEVBlog – covers many aspects of electronics. If you’re trying to learn specific things look out for Fundamental Fridays. The rest of the content is great for generally increasing knowledge of electronics.
Books
Books are still a great way to learn, as the format requires authors to cover subjects in a reasonably complete, organized manner. You might not find quality like that online.
Anything Arduino related should be a good start for fursuit electronics, but here’s a few specific recommendations:
Make: Electronics: Learning Through Discovery -This is a good easy introduction to electronics.
Getting Started with Arduino – A nice little book that not only gets you started with Arduino, but explains how to interface Arduino with various things (switches, lights, etc.) Even if you don’t get this book specifically, it should link you to other good Arduino books.
Practical Electronics for Inventors – A good general electronics book; it’s a bit of a step up from Make: Electronics.
The Art of Electronics – This is the definitive book for the electronics field, but I think it’s best for intermediate and advanced levels. When I first bought it I didn’t understand much of it so I bought other books. Over time as my knowledge increased, I was able to understand more and more of it. Nowadays I wouldn’t be without it.
The Book of Cosplay Lights – Getting Started with LEDs – by Svetlana Quindt.
KamuiCosplay PDF, KamuiCosplay Print, Adafruit Print
Advanced Cosplay Lights – Animated LEDs – by Svetlana Quindt.
KamuiCosplay PDF, KamuiCosplay Print, Adafruit Print
Make It, Wear It: Wearable Electronics for Makers, Crafters, and Cosplayers – by Sahrye Cohen & Hal Rodriguez
Amazon
Reference Cards
Adafruit has these neat reference cards, and you don’t even need to buy them; you can just download them!
Magazines
Magazines are still a good way to get information as they are hopefully curated by people who know their stuff. And the ads are often just as useful as the content to help get a project going.
Nuts and Volts – This is what I subscribe to.
Make: – I never subscribed, but I guess it’s popular. It used to be expensive, but they sometimes have special offers, I got one in July 2017 for $20/year.
Diyode – Started August 2017. Australian magazine, but you can simply do digital-only elsewhere.
Blogs
The Embedded Muse – by Jack Ganssle
More YouTubers
The Signal Path – very advanced stuff
Big Clive – mostly teardowns. The guy’s a hoot!
LED Projects – ¿Hablas español? Despite its name, it seems to cover all sorts of electronics, in Spanish!
Henryk Gasperowicz – So you need to fit your electronics in a really small space? Check out how Henryk does it!
ElectroBOOM (Mehdi Sadaghdar) – What NOT to do.