A comment in general:

Act professional and you will be professional.

If someone wishes to make a living by creating and selling 3D content and they don't think they need to be professional about it, they won't make a living by professionally selling 3D content. It is really that simple.

That means that you have to do more than just plaster boob shots all over the place when you're trying to sell shoes... Want to sell hair? Golly, maybe it'd be a good idea to spotlight your hair model instead of fifty different alluring face-shots. (And, please, stop it with the thirty different color filters on your textures. We get it - Yes, there are lots of colors in the spectrum. Thank you...) Want to sell unique morphs? Outstanding! Make them... unique. Want to sell clothes? Great! Spend some time learning how to rig, though. Oh, and don't forget that a texture and a bump map don't replace the need for real geometry. Want to sell dynamic clothes? Then don't just autogenerate whatever your magical clothing maker decides to cough up and call that a "product." And please, please... 3D objects are based on something called "geometry." Discerning buyers would appreciate seeing what your product's geometry looks like. If your geometry looks like poop, learn how to "geometry" so it doesn't look like poop. :) (Obey product standards and common conventions when constructing your geometry and groups. Thanks in advance. ;))

And, if you're doing your own marketing, please learn appropriate grammar. If English is not your primary language, get a friend to help translate for you. There's no shame in that. (Renderosity and other brokerages should be doing that by default, in my humble opinion.) If you're producing your own renders and graphics, please learn how. There's no "do art" button, but... for goodness sakes, if you're producing products for rendering programs you could at least prove that you tried to learn how to use the program you're creating for! It's a rare thing to see a decently rendered promo pic these days. A great promo render, focusing on the darn product being sold, would win half the battle for a possible audience to market to.

Know your audience. Know what they want and what you're going to have to do in order to give them what they want. And, if you don't know what they want, then know enough about what you're doing in order to convince them that your product is what they want. Fill a need or create a need - That's basic business.

If one wishes to make money with their hobby, there's nothing wrong with that. But, if one wishes to try to become a "professional" at anything, one has to do more than just fiddle around with it. Professionals take the time and make the effort to learn how to be professionals. If one doesn't do likewise, one will not be a professional. I'm of the general opinion that anyone who makes the effort and dedicates the time to learn a trade can succeed at that trade, no matter what it is. Unfortunately, many people base their expectations upon misconceptions. They have those misconceptions because they didn't take the time nor expend the effort to learn otherwise.