Hi, thank you for looking at my work. I checked your portfolio and I can't help but feel your work is quite professional already with light and color seemingly not an issue for you as it still often is for myself.
But just in case, I highly recommend Jeremy Vicker's Practical Light and Color from Gnomon - it's an amazing tour regarding color choice and realism and is often one of my more fundamental recommendations for budding artists more than anything else. (although as said earlier, your work is already professional so I won't describe you as 'budding' particularly - more like 'blossoming' instead?
As I gaze upon your work actually, I like how your work shows a lot of material roughness and grit, while I still often have an issue with hard and splintery objects like wood or rock still looking kind of... clay or melted. I hope you don't mind me turning this into a trade of sorts, but I'd like to know if you've got any resources regarding proper use of textures and so on.
Thanks, and keep up the good work too!