I would model any BP / C&B shop after The Log Cabin Shop in Lodi Ohio. The Kindig's there really know how to treat a customer and know every single product they sell, not one of those brothers are unknowledgible.
I would also have consistant lower prices, not just this week and then raise it next, consistant and reliable lower prices. It does not need to be much 2 or 3% lower all the time.
CUSTOMER SERVICE - Many people as long as they know they are buying a lower quality made item, as long as it works, really like to be able to pick up a phone or walk in and ask a question about a product w/o gettinga brush off.
On site minor repair of the products you sell. Simple things, screws, wedges, nipples, grips and put them on for them right there, right in front of them as you offer them some coffee or to watch a new product video.
The next advice is very iffy to SOME, but I like it, DO NOT BE AFFRAID to sell a customer on a new gadget, model or improved item. Have a demo avail on a lock with a bad flint and a well chipped flint. A demo of a hot shot Vs Normal nipples or caps.... and do NOT be affraid to suggest they grab the new goodies.
Have monthly rendevouse with period music and some real over the fire foods, Civil war encampments, Rev War encampments. Even is you have a small yard or property.
Have full bore cannon shoots like Ashland Gun Club does. Amazing to me how many $8000 to $30,000 cannons are out there where the owners are itching to show off an shoot.
Sell complete outfits of firearm, powder, C&B, rod, flints or caps and a powder measure with YOUR Name and Number on it.... REALLY and I am serious.
Have monthly contests for hard to get items, such as Goex a .32 Hatfield or ????
It all comes down to do you just have customers, or do you have customers, friends and a business that can be fun.
Gringo