In terms of technology advancement in pinball, my learning has gone backwards. My first pin (probably 10 years ago) was a T2. This is what I learned on. LOT's of circuit board components. Replaced bridges, caps and connectors. Learned how to carefully remove the connectors from each board, take each board off and stare at the solder joints for broken or burnt connections. The continuity meter has become my best friend. Learned how to get those stinkn' batteries away from the boards as well.
Then I went to a System 9 Sorcerer. Still solid state, a bit simpler but the same still applies. Look for what doesn't look right on a circuit board. My Sorcerer was firing two coils at the same time due to a poor solder job on the back of one of the boards where someone overflowed solder between two traces. It was immediately obvious once you took the board off. The continuity meter is your friend.
Then I went to a System 6 Firepower (which I still have and love). Dude, that game was playing the wrong sounds when switch hits were made!!! WTF! This was where I was introduced to bad chips. A faulty PIA chip on the sound board was the problem...but it took me hours upon hours of checking connections and transistors to figure that out. Once again the continuity meter was my friend. Also the ohm setting as well. After many hours of replacing old caps, a 5101 RAM chip (almost a necessity on early SS games) and desoldering and resoldering EVERY header pin on each of the boards, that baby is rock freakin' solid. After doing all that work I would recheck my solder connections for solidity and accidental bridging. The continuity meter is your friend.
Then my father hooked me up with a guy that wanted his 1976 Aztec fixed. Non-working game stored in a barn for 25 years. What's he paying me in? More non-working (and filthy) pinball machines. Two EM's. I'm like "sure, I guess I guess I can give it a shot." My experience with how switches worked was applied to the max when going over this game. Since I've had nothing but dead (or almost) EM's I found that going over EVERYTHING and cleaning EVERYTHING is the best approach for when you finally flip that power switch. Afterwards, there's usually not too many issues left.
Maybe get an early solid state game as your first. Gottlieb System 1's seem pretty simple. Also, while I use one of them cheapo 15 watt Weller for EM's, I have an analogue temperature controlled Weller with a fine tip for doing circuit board work. Much cleaner and less likely to burn something. And keep that tip clean.