The ceremonial solo pinball lift to put the legs on is the peak of new pinball day. You get a nice bruise on your thigh for a few days to remind you how much fun it was destroying one or both of your legs.
Don't engage in any modifications/renovations or anything you might regret without thorough research and practice if possible.
If you do take anything apart for cleaning, take pictures.
Look up the fuses for your machine and keep some handy to minimise downtime.
Don't use millswax, use a decent automotive or guitar wax.
Keep a bottle of isopropyl alcohol around.
Keep the playfield clean.
Keep the balls shiney. I'd replace them once a year under normal solo play or once every 6 months if played regularly.
Force your partner to play it, especially if they don't want to, and revel in beating them.
Enjoy it.
Don't worry about the money investment. You play this hobby smart you come out approximately where you started. If you break the bank vajazzling pins then then that's a you problem