For starters, this looks already good! c:
As inkling stated, the lineart should be more stable.
As for the background, you don't necessarily have to draw a realistic bg with a landscape. This is usually a bit difficult, so you can try to draw, for example lil bunny heads around her or dunno, lil flowers or something. If you use SAI, you can download custom made brushes. With these, you can draw easily nice and cute bg's. (for example check my siggy)
When you got more experience in this stuff, how about trying to shade it?
You could try blending or maybe soft cell-shading.