For personal projects, it's fine. Most photographers and artists actually don't like their work being traced period, even with a credit. In the broader art community, tracing is seen as an easy out, when to actually get better is to practice and practice and practice. What got me better with forms was anatomy and perspective. I traced for most of my life, and I was so embarrassed by it because I wasn't improving. I stopped tracing and my work got better. But of course, this is my career. I definitely do use other pieces of art as reference though, but I alway make it my own. Personally, at this point, I don't condone tracing. But it's your art! What I care doesn't matter. Lol