A good salesman knows two things: The customer is
usually right, and advice is nice, but cash is king.
As a salesman and technician at a small, privately owned computer repair/parts shop, I'm pretty much the equivalent of a resident gunsmith at a gun shop. What I've learned is that customers come in a few basic categories:
1. The novice. This person knows nothing, or very little about what he wants, and he freely admits to it. This is the type of customer where having extensive (and correct) knowledge about what you're selling/repairing is truly indispensable. This type of customer needs a certain amount of guidance to purchase what he really wants/needs.
2. The know-it-all. This person thinks he knows more about what he wants than he really does. The tricky part about this customer is you have to cut his BS carefully without insulting or deriding him. DO NOT just blindly acknowledge and agree with everything he says, if you know for a fact he is incorrect, when talking about important technical specifications or other qualities of a product he wishes to purchase, order, or have repaired. This can bite you in the butt later, if he is not satisfied with the actual product or repair work he wanted done, because he was badly misinformed and you didn't correct him before the order was placed or work done.
3. The quiet type. This person will come in the shop, ask if you have a specific product, and if you do not, he'll ask if you can order it for him, He'll often pay cash for a down payment on more expensive products, or full cash for a product you have in stock. This type of customer is the easiest and quickest to take care of. He comes into the shop knowing exactly what he wants, and goes about getting it with little fuss. He may or may not engage in small talk while you look up product availability with your vendor(s), but is generally fairly easy going as far as prices are concerned (he likely did research on how much the product SHOULD go for, and expects a certain markup from wholesale at a retail shop). This type of customer is rarer in my line of work since most of them just order computer parts online, but the heavy regulation of gun purchases by the FFL system necessitates their patronage of gun shops for acquisitions so you're likely to get more of them in that business.
There are other types of customers, but I'd say those three comprise about 95% of my customers. There are also chatters, tire kickers, bargain hunters, and for lack of a better term, annoyances, but they're in the minority, at least in my experience. Your mileage may vary, of course.
You also need to be very, very detail oriented in regards to the ATF paperwork such 4473's and other book keeping requirements.
This should be stressed as well. Gun shop records are scrutinized
very closely by a lot of people, so crossing your t's and dotting your i's is essential.