Basics as a salesman

Shop Keeper, Bartender, Gun Dealer

Having your shop
Build a nice little shop, advert it, and wait for people to come.
If you want people to stay and return, you need to be nice to them.
Wrong: "hi"
Right: "Good day sir! Would you like something to drink?"
or, as a gun dealer: "Good day sir! What kind of weapon are you looking for?"

Roleplay it.
Instead of just spawning a beer on the bench and say "thx", you can use /me commands.
/me taps a beer.
/me puts the beer on the desk.
That'll be $30 sir.
/me takes the money and puts it in the cash register.
Have a seat and call me if you need a refill!

Or as a gun dealer, you can talk about the weapons:
"Ah, the Desert Eagle! A very powerful pistol but with a small ammo clip. Great choice!"

I like this guide. Businesses should actually feel like businesses instead of 'Insert money here'.

I'll be sure to use this if I ever become a gun dealer (usually has 'the regulars')