There's no easy answer to this. What works for me and my locations won't work for someone else in a different situation.
There are so many things behind the scenes with each scenario. If you have a store selling games you have the cost to get the location ready, rent, inventory (games are expensive), employees... And if you have a crappy location you're sunk no matter what.
If you are an operator you have to have enough locations to make it worth while. That isn't necessarily easy to do depending on where you live. And the restaurant/entertainment business is very fickle and often short lived. You could have a location that is gangbusters for a year, next year it is closed. You need to rotate games and have a place to store and work on them. There are so many little PITA things when operating games that you'd never think of. I've written extensively on this in the past so I'm not going to rehash it. You'd be amazed at what breaks, how often, and the crap that happens at the locations that adversely affect how much money you make.
If you are doing repair work you have to know your shit. If you don't, you'll spend time on return visits and do a lot of driving to fix your mistakes and/or what you overlooked. Or you'll piss off a lot of customers by not returning to fix your mess. And if you do that you'll get the reputation of being a tail-light repairman that won't stand behind his work.
If you operate or repair you'll need a fairly extensive inventory so that you can fix whatever breaks without having to order parts and waste a return trip. Last thing you want is a game down for days while you have to wait on some piddly part that you don't have on hand. You'll need working circuit boards for testing and diagnosis. If you operate you'll need working boards to use as replacements to keep stuff running.
Then there are the things that apply to any business: Permits, licenses, liability insurance, taxes. You may be 19 but you need health insurance. And you need to be saving something for retirement or when you can't physically work any longer. That day will come no matter what you think.
I could go on but I'll stop there.
