I'm in the same boat on you with this issue, making something aesthetically pleasing enough to buy or upvote is pretty tricky. Maybe persistence is the key. Maybe the more you post, the more you get noticed. But would it be better to make many posts of low to mid quality artwork, or make very small amounts of posts of very high quality artwork. It is said that one can not rush creativity. I don't really know, all I can do is observe what the successful people are doing, analyze them, look at their profile. How did they get successful? Philosophize and analyze how does one become successful posting their art online on steemit, would be my advice, as I am only new to steemit.