1. Treating other artists or craftsmen as competition simply because they market a similar product. That guy at the table beside you who sells badges too? He's not your enemy, he's a potential future collaboration partner. He has customers exclusive to him just as you have customers exclusive to you. Encouraging your customers go check him out will not diminish your business but will actually enrich it as your customers network with his and talk them about who sent them.2. Having a crisis every week. We all have legitimate problems and reasons to legitimately have sales to try and raise money. I am not calling people out who need emergency car repairs or surgery money or need to pay off a surprise bill. I am calling the people out who claim on a weekly basis that they need money or they are going to lose their house/car/cat/whatever. If finances are THAT tight then go get a part time job flipping burgers. I feel the same way about people who go to conventions and claim that if they don't make a profit then they'll starve and lose their house. If money is THAT tight, don't go to conventions.3. Treating clients like crap. I've heard of people who snark about their customers and who jump down their throats for asking innocent questions. During one convention I walked up to a dealer's table and started asking them about one of their pieces. I was asking about technique and little things like that and the artist responded with the biggest condescending comic book guy channeling tone I'd ever heard. They might as well ended every sentence with “DUH!!!” The object I was asking about was for sale for several hundred dollars and I was seriously considering buying it. But then I decided my money should go to someone that actually showed me a little respect and thusly, I moved on.4. Blaming the customers for bad sales. If a restaurant opens for business and people don't like the way the food tastes, is it the fault of the customer for not liking it or the fault of the chef for not making food anyone wants? This is why when people complain that they have to draw porn to make any money it sends me frothing. I'm making more now drawing art than I did at my old job and I don't even draw nipples. (Allow me to say that I know that if you START to draw porn and then stop, breaking free from that is difficult because that is what your previous customer base wanted.) But really, if you don't sell things then instead of pointing fingers look into ways of improving sales and things for you. Advertise, try new products, and sometimes you just need to ask someone, “what do you like to buy at conventions?”5. Encouraging drama. There is one great rule of the internet and that rule is that people out there will not like you, will complain about you, badmouth you, and potentially even try to undermine you. You know what? Fuck them. If they actually have the time to do all of that then they aren't very busy being successful, are they? Don't fan the flames, don't acknowledge it, don't start it, and for goodness' sake don't drag it out into the open. I learned all of this the hard way but you know what... I LEARNED. Just put your head down and work. You'd be amazed at how effective that is. And lets not forget to mention the fact that a lot of your customers might not want to get stuck in a drama shitstorm and may choose to avoid you because of it.6. Punishing all your customers for the sins of one or two. Taking down your whole gallery, slapping on huge watermarks, handing someone a phonebook thick pile of rules and regulations they have to follow to so much as consider getting a commission from you... none of this makes you attractive to your clients. I do understand people making it clear that they don't want their art distributed and understand taking measures against it. But if you're trying to make a living with art, removing it all from public view or obscuring it doesn't help you. People that plan to steal your art will do it anyway and it's doubtful any of them will actually buy something. Punishing paying customers isn't so bright.7. Relying on the internet for validation and self esteem. “I don't know why I try anymore. My art sucks. Nobody wants to buy anything anymore...” This sort of ties into “Don't encourage drama.” Basically if you have to use pity to get attention and sales you are doing it wrong. If you have to do it to get any sort of motivation or validation to do your work then you are REALLY setting yourself up for a let down. It's a boy who cried wolf situation. Do it too much and people will get so used to it that they won't be there if you ever REALLY need them.8. Not following through. Rome was not built in a day. All too often an artist will try something and then very quickly get bored with it and quit. People ask why my livestreams are successful and I tell them the same reason time and time again... because people know I will be there on a schedule. It's the same with Little Tales. The webcomic does well because I have updated on schedule for over three years. My production hasn't been perfect, but I've never vanished off the face of the earth for a month with no explanation as to why. You can't start a new project and then give up on it when you get bored if you want to be successful.9. Lack of marketing. Advertisement is not very expensive. Space on FA, on project wonderful, in conbooks will get you lots of hits digitally. There are also business cards that will do you plenty of good. Just drawing sometimes isn't enough. You need to let people know you exist and the adage of needing to spend money to make money is all too true.10. Greed. This ties into the other ones in various ways, but is an issue big enough to merit an entry unto itself. Someone once told me how they commissioned an artist to draw their character which was a white fox in a black shirt, thus they only wanted pen and ink. They then asked the artist when they were finished if they could color in the eyes. Two little dots of yellow that would have taken a second of effort. They were told no, doing so would make it a color picture and they'd be charged the rate of a full color picture. Getting paid for your work is good. Being mercenary about it is not so good. Learn when to give a little, when to cut a customer a deal, and when to lay off that guy who just wants to look. I have people in my streams who have never bought a thing, but because I don't push them or make them feel like they have to buy things they have encouraged their friends to come in who have bought things. It does pay off in the end.