Absolutely, Thank you Ben! I'll add this to the top post shortly too. I am absolutely going to try hand-made textures next time I give it a go.
I was using the paint brush tool (not sure what it's called in GIMP) to paint the entire texture from scratch whereas you started with a solid "base color" layer. That's kind of a no-brainer, but I hadn't thought of it. 
I was ending up with a harsh step between color fields that I really didn't like in my hand painting attempts. You painted in multiple layers of similar colors and used what I think was a "soften/blending" tool to smooth it all together in the end. That made a huge difference. It also looks like there is also a good amount of talent/knowledge involved in knowing where to put the shadows and the highlights. I learned a lot about head-shading from your video, and I expect I just need to find references for other models I make, and eventually I'll learn.
Near the end, it looked looked like you applied an effect to the entire image; was that a hue change, saturation adjustment or something else?
I was using the paint brush tool (not sure what it's called in GIMP) to paint the entire texture from scratch whereas you started with a solid "base color" layer. That's kind of a no-brainer, but I hadn't thought of it.
I was ending up with a harsh step between color fields that I really didn't like in my hand painting attempts. You painted in multiple layers of similar colors and used what I think was a "soften/blending" tool to smooth it all together in the end. That made a huge difference. It also looks like there is also a good amount of talent/knowledge involved in knowing where to put the shadows and the highlights. I learned a lot about head-shading from your video, and I expect I just need to find references for other models I make, and eventually I'll learn.
Near the end, it looked looked like you applied an effect to the entire image; was that a hue change, saturation adjustment or something else?