How To Start A Coin Business?

Unfortunately you may well be to late. Sort of like all the stores that opened up some time ago selling or renting VHS or BETA tapes for TV Movies. They popped up everywhere. Then naturally all the big stores and even grocery stores jumped in on that. Now almost all gone and any left now sell shoes or something.
However, back to your problem. You must remember to own any kind of store, you'll need to pay for rent, electricity, phones, water, gas, etc. Then there is showcases, safes, lighting for the showcases and the store. Air conditioning, heating, chairs or such and lots and lots of coin collecting stuff. All this let alone coins for sale. Advertising could also become expensive. Now after all this, a location for such a store must me in a place where you can get lots of people to stop in. Good parking for cars may be a necessity.
All of this is why so many slowly fade away.

In March, I will have had my ebay store for one year. It truly is only a hobby business. I'm not making a killing, but I do enjoy it. I would suggest you first try selling on ebay, then if you are successful, maybe do an ebay store. Good luck & Happy New Year !

There are a lot of shops in my area, that do really well. I am in the suburbs of a large city, so thats why. Try to get a location near a large city

Don't forget to put arms and ammo in all these monetary projections. I wouldn't have a store with that many assets without arms.

You could work as an assistant to a coin shop owner for a few years before going out on your own. I'm sure an insider's perspective is much different than our perspective (outside looking in). Setting up a coin shows or flea markets is another option to make sure you don't invest too much before you know if it is even feasible. You may have to carry other items to make a go of it, several of the coin shops in my area have large selections of jewelry, antiques, and other collectables in order to supplement the bottom line.

I would think that many of us dream about running our own LCS, The same way drunks dream about owning a Bar
It would be fantastic to spend the days chewing the fat with fellow collectors and teaching the "New Chums" about numismatics and still earn a living doing this.
Sadly the Reality is that the days of the little LCS shops are numbered and the bigger more established players that have also embraced the internet will be the only survivors at the end of the day

The ebay option is OK but usually ebay is the main "Winner" and you will have to deal with various "Numbskulls" that you will definitely encounter when selling on this platform.

You could create your own website and sell from there cutting out the ebay fees but you wont have much exposure until you become a well known seller.

So don't quit your day job just yet and just "dabble" at being a dealer for a couple of years in your spare time to see how it pans out for you before making any drastic decisions

In my city, the few LCS that are left make about 1/2 their business from buying and selling bullion and precious metal jewellery. If that does not interest you then it might be difficult to make a go with pure numismatics.