Steps: 6 or 7
Includes: Optional Channel Mixer
Suggestions: Deep blues and magenta are the best colors for rich colored icons. Oranges and greens with the optional step create the best overall finished product if you choose to use it. Watch out for the saturation layer because the skin of your "model" might become overly-saturated and have the appearance of an extremely bad tan...
Examples under the cut: Pete Wentz of Fall Out Boy and Nightmare of You
Step One: Crop your image to 100x100, sharpen if needed, etc.
Step Two: Layers->New Adjustment Layer->Brightness/Contrast
Step Three: Layers->New Adjustment Layer->Hue/Saturation/Lightness
Step Four: Create a new raster layer and fill it with #716b7d, Soft Light 100%
Step Five: Create a new raster layer and fill it with #fb5356, Luminance (L) 30%
(L) Legacy? Legacy simply means the blend mode will act as the previous program did when that blend mode was selected. For example, I have PSPX2, therefore when I select legacy, the result of that layer will look as if I had made it in PSPXI on Luminance. Basically, each program handles the luminance blend mode differently and the legacy option just gives you a little option (This goes for Hue, Saturation and Color as well). You might want to switch between Luminance and Luminance Legacy to see which blend mode looks better.
Step Six: Duplicate the base, drag it to the top, Overlay 33%
(Optional) Step Seven: Layers->New Adjustment Layer->Channel Mixer
112, -12, 3, 0
(112: red, -12:green, 3:blue, 0:constant)
3, 94, 6, 0
(3: red, 94:green, 6:blue, 0:constant)
21, -21, 92, 0
(21: red, -21:green, 92:blue, 0:constant)
I'd love to see your result(s) :]