I'm not sure what everyone is trying to say is coming across right. Your contrast is not aggressive enough, especially towards the darker shades. Don't be afraid to use dark colors! Look at this, for instance.
![[Image: oaQeefw.png]](http://i.imgur.com/oaQeefw.png)
I've edited your mushroom. You may noticed I've gotten rid of some banding at the bottom, and changed the colors. I've compared the properties of our colors:
http://imgur.com/PDd8yuS (top are yours, bottom are mine)
Hue shifting aside, you can see that the darkest shade in mine is considerably darker from yours. Since that color is reserved to the outline, it gives the object a more 'solid' feel, and additionally makes the other shades stand out. At a larger scale, you might be able to get away using low-contrast transitional shades, but at a small scale, you're better off using a small number of high-contrast shades.
I've edited your mushroom. You may noticed I've gotten rid of some banding at the bottom, and changed the colors. I've compared the properties of our colors:
http://imgur.com/PDd8yuS (top are yours, bottom are mine)
Hue shifting aside, you can see that the darkest shade in mine is considerably darker from yours. Since that color is reserved to the outline, it gives the object a more 'solid' feel, and additionally makes the other shades stand out. At a larger scale, you might be able to get away using low-contrast transitional shades, but at a small scale, you're better off using a small number of high-contrast shades.