This page provides an overview of helpful books, communities, (web)shops, and technical specifications of specific parts I have come across.
Some nice introductionary books I've come across:
There are many great places to find help:
Of course, a good place to buy components is at large manufacturer / brand stores:
Most of these products can also be purchased at local stores, or at national or European websites. This'll save the hassle of customs and exuberant postage fees. Good examples with which I have positive experiences are:
Sometimes, reading the (formal) specifications of an electronic component can be very helpful, and even prevent you from making huge mistakes! Below, I'll list some useful documents of my incorporated components: