it's not that it's hard to sell, it's just hard to advertise. so you have to mention yourself everywhere, have lots of keywords. put yourself out on facebook, twitter, google and whatever else is around you. it should be in your mail, etc. always have lots of things to choose from, make sure the quality is high - don't compress images if you can help it, if you paint or draw make sure you use a scanner. if the image is blocky, noisy, blurry, etc, the printers may not print it. make sure to have descriptions on everything and good titles. while it may not help the internal engine, it will help for google. always upload your best work. it takes time to sell, anywhere from a few weeks to many months. it all depends how much you put into it.