Lots of steps. Includes such things as selective colors and curves. Not recommended for beginners.
First off, we have our lovely screencap from the opening sequence of the new Death Note anime.
Time to cut her down to size! Crop, resize, and we have our base.
Now the fun begins.
1. Use levels to add some contrast, brighten the whites, and darken the darks...but not too much. We don't want to overdo anything at this stage, so just remember that you can always go back and level more if you really need to.
2. Duplicate your base layer and set it to Soft Light at 45%.
3. Add this layer by dearest and set it to Overlay at 100%.
Yeugh, I know this isn't looking too pretty at the moment, but we're not even close to done. :)
4. Select the smudge tool, and using a soft brush at size 35, smooth out the right half of the icon, taking care to smudge the light yellow line around so it's no longer a straight line. It should look something like this when set to normal:
She's looking better already! Unfortunately, she's going to look worse again soon, because that's how I operate. ;)
5. Time for the fun part. Make a new selective color adjustment layer. Really play up the reds, magentas and yellows. We're going to be adding more blue later on, so the oversaturated effect will only be temporary. Don't worry, be color happy! It's fun. :3
6. Make a new curves adjustment layer. Don't mess with the greens, but play up the reds a bit more, and intensify the blues. This will make the icon way too dark, but it'll lighten up in the end.
7. Add this texture by samuraiblues, and flip it horizontally. Set it to screen at 100%. This is just to add a little extra light and color. If you don't like it, it's optional.
8. We need to intensify it a little bit at this point, so duplicate your base layer, drag it to the top, and set it to soft light at 75%.
9. Add this gradient by meleada and set it to overlay at 100%.
10. It's looking good, but we really want to keep the right side of the icon dark. Using the eraser tool, I used a soft brush to erase the right half of the texture. Mine looks like this:
11. The hardest part is over, and it's smooth sailing from here! Now it's time for...a dark blue exclusion layer.
Oh come on, you knew it was coming!
12. Remember that layer just above the base? The soft light base duplicate set at 45%? Duplicate it, and drag it to the top.
If you like the intense colors, you can keep it like this. But depending on what image you're using as your base, you may want to lighten it up just a tad.
13. Create a new fill layer of #e8cbce, set to soft light at 75%.
14. Finally, add this gradient by omgIdon'tremember:x and set it to soft light at 50%.
And you're done! If you've gotten to this point and it just doesn't look right, it's probably your selective coloring or your curves. No worries! They're only adjustment layers. You can always delete them and make new ones, and there's no shame in experimenting, right?