Quoted from Fytr:

I definately wax none-CCed playfield regularily (based on games played). It makes a huge difference in how the game plays and looks.
For CCed playfields, I'll wax them once in a long while and then use Novus 1 for regular cleaning. Waxing a CCed playfield doesn't seem to do much for it. I doubt much wax actually remains on it after polishing to be honest.
I do also wax metal guide rails and such if they contact the ball. Shines them right up.
I use carnuba wax.

Quoted from mbaumle:

I've been using this stuff on most of my games. Works really well. I've also used the ever popular "Blitz Wax" but honestly, you can't really go wrong with Mothers either:
amazon.com link »