I browsed carefully your gallery and actually it's difficult to give you advice as most of the pictures here are not by you, and I'm not really qualified to judge litterature as I don't write much myself. So for the characters you've drawn, I don't know if you copied them or invented them but I think you could work on being more precise on the shape of their faces and eyes, and maybe start by drawing structures, it'll help. Before drawing the clothes, draw quickly a nude model to be sure that the anatomy of your character is not wrong and that his movement is possible (xD not joking, many artists draw their characters in positions that don't exist in real life). Otherwise, I admit that I first believed that you had drawn all of these pictures wheareas it's not the case. These pictures belong to you because they've been drawn for you, but if they illustrate a story then you should put them as previews for your texts. I'm not really sure about the fact that some picture built your popularity whereas you've not drawn them is really moral, but I don't know, because you own them. Take care !!!!