I think your style is perfect for a children's book. Your style of colouring sort of makes it hard to distinguish the background from the character, but it's still very unique and has a nice friendly feeling. Maybe if there was a way to differentiate the background with the character? Regardless, it looks wonderful.

Maybe I could try using darker or bright reds? or have a sort of white/empty-space around the characters?

Something like this?

>>42734
>>42733
Yeah! That looks pretty good. If you were to illustrate a children's book, I would definitely purchase it.

I don't know about this.
I really like the coloring, but I feel like the outlines might be a bit too "digital" looking. Maybe if you switched the brush you're using, or even when traditional for the outline, then the lines could be as warm as the colors.

>>42750

Maybe like this?

>>42754
Maybe.
Not that the boldness from before wasn't charming in it's own way, but I'd say the new lines look a bit better.

Maybe the Boldness for covers, but the more melded lines for the actual story?

For backgrounds, should I use a smoother brush? To make the characters stick out more from the backdrop?

>>42771
That's one way to go about it (or you could do the reverse,) but I would try playing with brightness levels, or experiment with the color-bleed outlines, either adding more white, or lightening some of the colored space around the elements you want to stand out. Mostly, I would just try to avoid flattening things out to much, but keep a coherent, real-media type feel, (neither of which hasn't really been a problem so far.)
Can't hurt to try a few different things, anyway. Especially if you can get a few samples of different styles together to compare.

You might want to look up the game "Okami" by Clover Studios. It has a Japanese ink brush feel that might work really well for research.