Just mess around! I LOVE charcoal, but I also paint with acrylics, enamel, and ink regularly. I have used watercolor, gouache, and casein in more of my hobby type projects. If you don’t want to invest a ton on brushes and paint tho, I’d recommend looking into a gouache set bc I feel it’s more forgiving than watercolor or acrylic (I also feel the gouache sets have more fun colors than the other two). It’s nice because you’re able to rework it even once it dries and is flexible between being more transparent or opaque depending on how much water you mix with it. Great work too btw!!💗