well the lineart is ok, but the coloring does no justice to the piece. The grass is alright, but everything else, especially the textured brush crap with seemingly random colors around the edge seems poorly thought out. You may try just a solid white or offwhite, or continue the grass and sky to the rest of the piece.

On the dog, the main problem is all those white bits. I would suggest start by coloring on a layer between the background and the lineart, and use a solid brush to completely fill in the character (not the fill tool!), then use a darker or lighter brush and add shadows/highlights to give it depth.

Last of all, as I've mentioned before, the copyright notice is really tacky. Personally I'd leave it out altogether until you're actually good enough that someone might want to rip you off. Anything you draw is automatically copyrighted whether you put that stupid little notice or not. If someone wanted to use it without your permission they could easily erase that copyright message anyway.
If you actually want to include, I suggest making it a lot less obvious (the copyright notice has a bigger presense than the drawing itself!). You could use a thin brush and write it very small, or simply use the text tool and put it in the corner of the picture out of the way and not distracting.

that copyright notice is really tacky...

ooo... wow... cool style... me like... lookz like that dude too. ^^

wow, beautiful, I love your dragon............

Wooooowww!! Swirly and curly!!

I've never seen the Anime, but I knew who she was :DDDD It looks so incredible!

I think im in love with u ^^

p.s. it's arigatou-gozaimasu (?????????)

this is cute...

try adding some more shading/highlights and a bg?