Quoted from robx46:
I can learn a bit about electronics & working on circuit boards, or I can get greasy working on some mechanical stuff, & when I'm done there is an awesome game to play & art to look at. Honestly is there a better hobby out there?
This sums it up pretty well right here, and is exactly what I have done. Buy small, clean and fix, trade up. You will learn along the way, and many here will help.
Quoted from UvulaBob:
I've been poring through this book on electricity to learn about volts, amps and ohms and I have my eye on a couple of general pinball repair books on Amazon. I've watched pretty much every video by TNT Amusements, PinballHelp, havepinwilltravel, S Verlander and a few others.
Great start and good attitude, now go get a Pinball Ninja membership. Best 20 bucks you'll spend on the hobby.