Really glad to see you keeping at this. I don't know if what I'm about to say has been said, but I Think you should give the hair an outline, especially because the rest of the body has one. And also, the mouht's a bit weird for several reasons, and there are different ways to approach this.
The problems with the mouth ( that I see at least) are that it blends to much with l the skin, and has WAY too many colors. The teeth don't need any shading at all, yet there are three shades, which aren't even that visible. You also outlined it, which you could definitely do without. It might be best to try not to include things like teeth or lips, as they're details that are to realistic, and that kinda takes away from the chibi style. I'm no expert on this, and I only have a bit of knowledge on the subject, but basically, there's a line between cute and realistic that can be seen as creepy. This isn't to close to that, but it's better to stay closer to cute and simple by removing the teeth and lips.
also the grey outline thing around the yellow line on the boots isn't necessary, I'll put my edit below. I didn't cover everything i edited, nor did i edit in everything I covered. Sorry.
Ah, also, If you're gonna outline, do it all black, and don't outline too frequently. I'm sure someone out there made colored outlines work, but I suggest you stick to normal black outlines.
