First, I want you to first make sure your paper is Copic friendly, I use Copic Xpress it Blending Card. Sometimes, you’re not doing anything wrong but the paper isn’t heavy or smooth enough. After that, make sure you aren’t going back over the dark colors with the light, in short, making your darker color separate and causing blotchiness. On the other hand, another thing that might be happening is you’re not adding enough color to the paper. So, if you’re using R81, R83 and R85 to color and it’s not smooth. Add another layer in that order exactly how you laid the color down the first time.