Icon Tutorial #1
This is my first tutorial, it's simple but I hope you'll find use of it.In this we go from this:
to this: 
I started with this picture and cropped it to this:
The first thing I do (with all icons) is to sharpen it. That way all the details will come out.
Now I lighten it by duplicating the layer twice and putting both on 'screen'.
Then I make a new layer (ctrl+shift+N) and fill it with a dark blue colour (000A3E) and put it on 'exclusion' 100%. It should look like this.
The next thing I do is create yet another layer that I fill with a brownish kind of green (A9BC70) that I put on 'color burn' 50%. It brings colour and contrast to the icon.
The next step isn't the most important, but it makes the icon just a tad darker. You make two new layers that you fill with a very light colour (I chose a light blue, E5FFFD) and put on 'color burn' 100%.
Then you make another layer that you fill with a clear blue (9DF5DF) and put on 'color burn' 100%.
The final step is to duplicate the original layer, drag it to the top and put it on 'color burn' 50%. Now your icon should look like this:
If you want you can add text or anything else.