Long time lurker, first time poster. :) This is for one of my favorite icons.. (I say this because, even after months of making it, I don't crinkle my nose and go "eew" :D)
For this
From this
Not very image-heavy, as I have yet to master screenshot-ing every step. And maybe not for the beginners, since I didn't give every eensy weensy detail for every step.
Oh, and this was made in Photoshop CS. I haven't used any other program, so I don't know if it's translatable or not.
This was way back when.. Back before I knew about selective coloring, levels, and all that other tinkering short-cuts. My theory used to be: If it looks good in color, it should look good in black and white. :D So here's my (slightly outdated, but still hopefully useful) technique:
(I forgot my source, but I found the picture from a Google Image Search I did of "Mr Tumnus")
1) Take your base and and sharpen once.
2) Duplicate your base twice, and set both to SoftLight 100%
3) Create a new layer. Go over the background with AADBF4 (a light blue). Don't go over Mr Tumnus, his packages, or his umbrella! Set this layer to SoftLight 100%
4) Duplicate your base again and drag to top. Go to Filter >> Blur >> Gaussian Blur. I don't remember my settings, so just play around until it looks right. SoftLight 100%
5) He looked kind of orange.. So, duplicate base, drag to top, desaturate. (ctrl+shift+u) Screen 50%
6) But then! It sort of lacked contrast. Duplicate base, drag to top, desaturate. SoftLight 100%
7) But I decided that still wasn't enough of a contrast.. So.. Create a new layer, and fill with 000000 (black). Set to SoftLight 100%
8) I decided I was happy, so I put a black-and-white gradient map over it. Then I added a layer mask, and painted black the scarf and packages he was carrying (the parts I wanted in color).
Done! Of course, as is the mantra, this won't work for every picture, so you'll have to play around. :D (Or, to get a feel of it [and so you can understand some of my explanations], you can try it with the original base *points up*) Just don't claim as yours and I'll be very happy indeed.
Questions? Comments? Violent reactions? Please let me know! This was my first tutorial, and I'd really appreciate some feedback.