Sometimes (especially in the lighter colors) the differences between shades has to be more extreme, but as long as it looks good, it's no biggie. But I don't know what you mean that 'the color changes whenever you color'?
I already found out, though... I already solved the problem because I had to copy-paste it instead of save it. I figured that when I colored it the picture only allowed me to use the colors that were on the base only.
Hmm... If you want to. The best thing is this situation is to look up other tutorials on how to shade dolls and once you feel like you have a decent grasp on how to do it, that's when you make another tutorial.
I say keep this one up. Use it as a reference for when you improve. ^^