/ic/ - Artwork/Critique

Hi anons, I've been struggling with rendering for a while now. I can't identify why everything I render looks so messy and not clean, I try to take my time and analyze what I'm doing wrongly, but I just can't find the error in my ways. My linework also "doesnt work" in combination with the rendering, causing me to erase certain parts of it, making it more transparent so that it isn't really visible, but I really hate doing this and instead I want the rendering and linework to work with eachother. pic related is btw referenced from one of yoshinari his drawings.

Can some fellow brother anon offer some insight in what I'm doing wrongly (and/or what I should practice to get better in this).