-Open new document, any size (I used 420x300 default), fill with white.
-Make a long oval selection
-Use the rectangle selection, set to subtract, and select the bottom half of the oval. You'll be left with this:
-On a new transparent layer, fill the half-oval shape with color. I chose a bright green.
-With your selection still active, Select>Shrink your selection a little bit. I shrunk mine by 10, but this amount will vary depending on how large your image is.
-On a new transparent layer, fill this new selection with white.
-Using the move tool, hold down the alt key and move your selection down and a little to the right. Edit>Clear (ctrl+K) the selection. I also lowered the opacity to 60%.
-On a new transparent layer, make a circular selection. Holding the Shift key will make your selection perfectly round. If your circle is not positioned where you would like it, you can use the move tool with the alt key to reposition your selection. (see above example)
-Fill this selection with a skin toned color. I used ffe3bb.
-Select>Shrink this selection (I used 10 again).
-On a new layer, fill with white.
-Using the move tool, with alt pressed, move your selection down and to the right just a little bit again, leaving a crecent shape. Clear the contents (edit>clear or ctrl+K). Lower the opacity of this layer to about 60%. You should now have this:
-Using a round brush, on a new transparent layer, make a dot of white on the crescent shape on the head.
-Filters>blur>gaussian blur the dot. I blurred by about 10.
-You could be done here, if you wish! Or you could add a few more details.
-You could add a little face, a drop shadow (Script-fu>shadow>drop shadow), or more people!
This is my first tutorial, so if I was unclear about anything, please don't hesitate to ask!