Easy way to customize the icon (and/or color) of desktop icons?


Many of my desktop icons have the same icon and color. I would like to customize them. How can I do it? I tried looking in the DocType but it seems the icon there already refers to another icon! (In fact it refers to a quite suitable icon, but for some reason it does not show up on the actual desktop icon). How can I customize this easily without coding. Thanks for any help!

As explained by @lasalesi in this thread: Changing in-built icons image on desk - #16 by lasalesi