My 2 cents:
After unboxing, be sure to visually inspect the game above and below the playfield and check for any loose fasteners from shipping.
Since it’s a Stern, toss the balls it came with out as they wear very fast by all accounts. Ball wear is what most directly cause wear elsewhere. Be sure to clean any oil off the replacement balls with alcohol/windex before using them.
Wipe down the playfield with a microfiber cloth to remove any residue from assembly/packaging/transit.
Then you can fire up the game to make sure it works properly before doing any additional work on it.
You then enter the realm of optional things that you’ll get a bunch of different answers on. I know on my new games, I’ve switched them over to silicone (Titan) rubbers to keep the black residue from building up. As others mentioned, keep an eye on flipper slop/play as the coil stops Sten uses are very poor. On my GZ, I went ahead and replaced them with new Pinball Life just for piece of mind.
You’ve already done the most important things - came here and read and asked questions.
Welcome aboard the boat or table or whatever you want to call it here.