I am not a fan of UNSHARP mask in Photoshop, but I know that many photographers still use it. So if you must use it, here is a way to reduce the ugly halo effect that unsharp mask can create on color images.

First convert your image from RGB to LAB color space. Then apply the UNSHARP MASK to only the LIGHTNESS layer in the CHANNELS palette. This will bring out the detail and will make your image appear sharp without shifting your colors or creating halos.

Then you can convert back to RGB.