tutorial: icons
Made in GIMP 2.6, but probably usable in other programs.
Turning this
into this
The main image
File » Open, and open your chosen image.
Make whatever brightness, contrast, color, or sharpening adjustments that are needed, depending on your image.
Go to Toolbox » Foreground and Background colors, and set the color to #fff2de.
Choose your preferred brush, and set the opacity to anywhere between 20-50, depending on your image.
Gently start to color over the skin. You should get a smooth, pale effect. It it's needed, go to Toolbox » Blur/Sharpen, and set the Blur rate to 85%, and quickly run it over the finished skin, to smooth over any blemishes or mistakes.
Go to Colors » Brightness/contrast, and set the brightness to anywhere between 20-50, and the contrast to about 20.
Make any final adjustments, sharpening, coloring, etc., and you're done!
The eyes
Zoom in 400%.
Go to Toolbox » Foreground/background color, and set it to #00f6ff.
Go to Toolbox » Brushes, and choose a brush, then scale it down to preferred size.
Set the brush opacity to about 80 and then color over the irises of your subject's eyes.
If needed, go to Toolbox » Dodge/burn, and set the Burn to ''shadows'' and 30% exposure, and run the brush over the eyes, to brighten them.
Touchups
Scale the image down to your preferred size (it always depends on the image) and sharpen it slightly.
Go to Toolbox » Dodge/Burn, and set the Dodge to 'highlights', and 20% exposure. Run the brush over your entire icon, and you're done!
This is my first tutorial, so I hope I've made everything clear! Let me know if I've missed something, or your icon came out completely different, and I'll look over the tutorial again and possibly tweak a few things.