2.Duplicate the base and make a color fill layer, #00FFFF (ofc you can pick any color you want :D). Set it to screen and merge down. Then set that layer to darken. Now we have.. wait, nothing happened? Move that layer a little bit to so you can get some color poppin' out. :)
3.If some parts look funny or if you want the color just in one particular part of the picture just use the eraser.
Okay, now duplicate your base again. Then make a color fill layer, I used color #ff00f6. Layer pallette should look like this (yes, it's Marilyn Monroe. I lost the original picture of this step D:):
(Tak paham ke? :)
4.Outcome isn't that pretty yet:tengok je la
5. Set layer to screen,
6.merge down and set to darken.
And again, it looks like nothing happened, but move the layer a little bit so the purple somes visible. Now assemble your coloured layers the way you want and voilá; your done :)
7.Okey siap -PS! If you're making icon with this coloring, resize your picture first. It'll look way prettier. :)