I'm no expert - I do have an FFL and would love to make it a full time business - but there is not a lot of profit in selling new guns. In my area the places that make the most on guns are the pawn shops because they buy used cheap and sell for a good profit at the market rate.
There is a lot more profit to be made in the accesories - knives - reloading - ammo- holsters - ect.... However, if you open a gun shop - as has been said - unless you have a good inventory of new guns at reasonable prices you will not have a lot of foot traffic - people just don't come in the door for accessories.
Also, depending where you live, city officials are often, (in the east, west coast, and parts of mid-west), hostile to gun shops and tend to create barriers to opening a gun shop. If you did get an okay, it is usually in a less than desirable location, which means a lower rent part of town - where there will be less foot traffic and more exposure to criminals likey to rob or burglarize.
If I someday am able to open my own shop, I will have to really learn gunsmithing. That would go a long way to making it more likely that I would make a profit.
From what little I know or have been told.
1. Get a decent location
2. Carry a good selection of firearms
3. Order guns for customers at reasonable prices
4. Sell used guns
5. Gunsmithing
6. Carry lots of accessories and make it known you are happy to quickly locate order hard to find items for a reasonable price
7. Be polite but helpful
8. Don't let friends or gun shop commandos take over your shop, be friendly but firm
9. Advertise
10. Sell other sporting equipment
11. Don't plan on making a profit
