The purpose of this tutorial is making an image more appealing. We'll work with this image made by cdcguard and posted at morguefile.
As the image is pretty big, we're gonna work with a reduced version:


My result after following the steps explained in the tutorial:

Sharpening the image

As you can see, the image is a bit blurry, so we're going to fix that.

1.- Duplicate your base layer (the layer where you have the image) by clicking Ctrl + J or going to Layer >> Duplicate layer
This is important. When you're going to modify an image, always work over a duplicated layer from the original image. In case you don't like the effect, you only have to delete this duplicate layer.

2.- Go to Filter >> Sharpen >> Sharpen to sharpen the image.

Making the image look realistic

Our image is now a bit dull. To fix that, we could use some Adjustment Layers, but let's try something different.

3.- Duplicate your sharpened layer, and set its blending mode to Soft light



If your original image is too dark, you can use some Screen layers too.

Coloring

As you can see, the image colors look a bit weird, maybe too blue. So now, time to some color effects.

4.- Create a new layer Layer >> New >> Layer, and using the Paint Bucket tool ( or pressing G), fill this layer using a dark blue #040e35.


Set this layer to Difference




It still needs some more color, so...

5.- Create a new layer again, fill it with the same dark blue, set its blending mode to Difference and its opacity to 50%.


And that's it!

Final result

Layers used:


I hope you liked this tutorial. If you have any questions, or something isn't clearly explained, please tell me.

Great use of the difference mode!

Well explained PSGirl, thanks for adding!

Another great tutorial with nice results, thankyou PSGirl

Nice tutorial, PSgirl!

Thanks for adding it!

I saw the image in your blog. Thanks for the tutorial!