Trial and error Dude. I completely strip the upper play field ( if you are comfortable doing that)I clean with spray and wipe initially if very dirty. Followed up by Novus 2 on general in ground dirt then if really bad shellite and Magic eraser, not too hard though. When satisfied I then use a finishing wax like mills wax, I love this stuff, most don't.
With out getting into it, on a restore I also use treasure cove pinball polishing system, excellent product and can also polish Mylar so it is very nice and slick. I only use carnauba wax provided after this polishing method.
Plastics I use windex . Flipper bars I soak in oomph( Orange oil) or just replace.
The more you do the more you will find your own groove.
The journey is half the fun.
Also have tumblers and ultra sonic cleaners, that's yet another story.
