The hair at the top is a litle cuted =\
The flower at her left has a litle white part at it, easy to fix
You could make that grass a litle better, or even take it out, put more flowers going down and make the bg better...improve those clouds

In general, the image and the bottom are well, but I believe that what fails, is the effect that you have put as of “grass” and the letter you could put it ^^U more down, and with the smoothest texture ^^ luck with it!

Firstly, she is very cute. And the overall concept it cute, too.

Now, down to business... ^_^

~ Her loop of hair up on top of her head is cute off. It needs to be repaired.

~ There is also some white showing by the loop of hair that needs extracting. I can't really comment on the rest of the extraction as the wall is overall so light that any extraction issues blend in.

~ She is very pale. You might want to look up some cleaning tutorials and brighten her up a bit. All the colors are very muted.

~ The grass is much too uniform & thin. There needs to be more & facing all sorts of directions. There's lots of tutorials on it. Frankly, I'd get rid of it altogether. If she's really standing in grass then it's so high it goes past her knees!

~ Placement. I'd say this is a good wall to apply the rule of thirds to. Scoot her over a bit so there's not so much empty space on the left. But don't center her.

~ The clouds are nice but there aren't enough. There's a lot of empty sky to the top of the wall. You may want to try scooting the clouds up so they aren't so low. Those kinds of big clouds are usually high up in the sky.

~ The text is nice but would probably do better bigger & with a touch of color. Also, because everything on the wall is so soft, it doesn't seem very "sunny". Maybe brighten things up. Add some sun rays or the sun itself. The shadows on her fall like the sun must be to the extreme left.

~ Lastly, maybe a tree or more blossoms blowing around rather than just having them centered around her.

The grass...it looks too clean cut, almost no texture. The bg...is it a photo of the sky? Cuz the stuff look too realistic for the stock...or maybe you're just really good at making clouds/sky. The stock is very very bright, and maybe if the text used a different font, it'd look nicer. The position of it needs a little bit of work too.