Selective coloring, when used sparingly and in the right situations, can bring a dramatic effect to a photograph. This technique recolors certain elements in a photograph, making them pop out at the viewer. A warning, though, overuse of this technique can be very very corny. As such, this tool should be used with great reserve.
This tutorial draws on previous tutorials (Conversion to black and white using the channel mixer and layers). If you haven't seen that, you should watch it before you continue.
Thanks for that. I was attempting to do the same thing with the magnetic lasso tool, and it would always leave a line around the selection.