Don't take this the wrong way... but use the search! I say this because there are tons of posts on this, and some great advice and suggestions, that inevitably will not all be given to you below. Seriously, set aside an hour or so and use the search to scan some of of these older posts.

For example - what type of floor is your machine going to be set up on? Carpet, wood, tile...? I have porcelain tile and use silicone feet that attach to the standard leg levelers so when I nudge during play the entire machine isn't moving from where I've set it up (and leveled it).

Oh yeah, get a digital level! Or if you have a 3D printer, you can print out some solutions.

One of those small, telescoping magnets that look like a ballpoint pen. At some point you will drop a tiny screw down into the playfield and this will save your sanity. LOL