Save your images as SRGB for the web
This is pretty standard, but if the color is looking inconsistent when you upload it, it may have been set to the wrong color space.
For all you professional designers out there, be aware that some Amazon pages say you can use a colorspace of CMYK instead of sRGB. We tested this and found this to be bad advice.
The default colorspace for the entire web is sRGB and if the image is converted to anything else the colors of an image will not be rendered correctly despite what some may say.
CMYK Doesn't Work For Amazon Images
CMYK settings will render color correctly for a CMYK printing press and Amazon’s software will not convert the image to match a CMYK color space accurately.
On the left is the CMYK version open in Photoshop. On the right is Amazon's rendering of the same image. You can see the colors are way off.