Here's a quick list of some of the things I use regularly:
The Manual - If you don't get one with your purchase, you can find them on www.ipdb.org
Novas #1 and #2 for cleaning and polishing.
Johnson Paste wax for the playfield (and even the cabinet sometimes since JP has a painted cabinet).
A digital multimeter - Something will always go wrong. You'll need this to help find the cause.
It's difficult to get to some of the bulbs on JP. If your game doesn't come with LEDs, you'll need replacement light bulbs and a socket set to get to them.
I have a JP for sale. What part of the country are you in?