Step 1.
After trying everything under the sun to clean playfields etc, I find "baby bum wipes" are excellent in cleaning anything pinball.
(wont hurt a babys bum and cleans up any nasty shit very well, no pun intended)
so they will not hurt your playfield at all. When everything is as clean as u can get it, the bum wipes stay white instead of turning black/brown.
Step 2.
For plastics and ramps, I find "Gumption" kicks ass better than anything else on the market. Doesnt leave scratches etc, and makes things like brand new.
Step 3.
Last but not least, is Mills Wax for the playfield with the Ttreasure Cove detailing kit. I dont use their polish's much, but find Mills Wax is better than anything Novus.
The spinning drill attacments work very well. All the treasure cove head attachments/sizes are great for any playfield requirements. I have used Mills Wax for over 3 years on over 30 machines, all different manufacturers etc, and never ever had an issue. Some people say Carnuba Wax etc, but the shine the Mills Wax gives is T'Riffic.
NOTE -Some people dont like Mills Wax because it is supposedly petroleum based, but every polish has something strong in it. I have even left Mills Wax on very very thick on a test playfield over night and not had an issue. (not that i reccommend that on any playfield, but it was just a test). You can then wipe baby bum wipes over the entire playfield after the waxing to remove any excess cleaners etc, so u dont get any white powdery dust being left behind.
I say Keep it simple. Happy Cleaning.