Something I've learned purchasing and working on my first 3 machines during the past year or so is to figure out what you are comfortable with.
I've found I am waaaay happier to pickup a game that is cosmetically good and mechnically broken. It's easier (for me at least) to track down a dirty switch or re-pin a scorched connecter than to do touch up paint on a playfield.
Get an idea of what things cost and what parts you can even acquire! I walked away from a decent deal on a wishlist machine because I wasn't aware of play field hard tops. I figured if I found a NOS playfield, it'd run me $1k, so I walked. Had I been aware of a $300 hard top, I might have made a deal.
Can you live with flaked up backglass, or are you going to drop $300 on a resto?
Cabinet busted, how comfortable with carpentry are you? Learning this the hard way at the moment after picking up a termite infested EM...which brings me to my next point: never believe a word the seller/owner says! Investigate for yourself! I wish I'd prodded a bit with my screw driver and I would have seen the live termites, instead I took the seller at his word that the damage was well old...made a fool out of me!
All that said, there is nothing more satisfying than picking up a dirty, broken old game and bringing it back to life
Welcome to the hobby, it really is a ton of fun!