Firstly I want to complement your use of textures here.

The clouds, bubbles and design on her dress set this piece apart from it's other anime peers. However it might behoove you to credit back to the sources from which you obtained the stock.

Her swing looks a little awkward just floating there, I might extend it to the edge of the artwork for a more complete, finished look.

Also, I think the sky would have more vibrance if you used the blue from the "Shampoo" text. The font blue has less gray in it and therefore looks more lively which would work well with the youthful mood of this piece. Speaking of fonts, I'm not sure if the drop shadow is needed and your work might appear more professional if it is left out. However your font choice is very fitting for the artwork and the series!

But overall, this is a very charming picture with a nice throw back to old pin-up art applied to anime. I certainly think your on the right track!