Get some beautiful fabric flowers of ANY colour and size and remove the petiole ( hope this is the right word ^^ ). Also you might want to remove some of the stuff in the middle of the flower, because you need a "basis" for your skull.
But do NOT remove the green thing in the center that holds your flover together. Never ever! >___<

For the skull, take some modelling clay and make a nice, smooth little ball ( my skulls were about 2 cm ). Press the ball on a plain underground to flatten the backside.

Then take a pencil with an eraser ( CLEANED! ) on the end and carefully press in the "eyes" with this eraser. You may take Jack Skellington as a model ^^ But make sure the eyes are about 2/3 of the skull size, that's for the "awww, CUTE!"-effect. Smooten the borders of the eyes with your fingertips and a very little bit of water.

With the writing-side of the pencil, carefully press two small nose holes under the eyes ( see pictures :P ). Let your skull dry.

Afterwards, put some clear varnish all over it and paint the eyes and the nose ( CAREFULLY!!! ) with the black polish. You also may add a little smile on the skull ;)
After everything has dried, glue the scull to the middle of the flower!

Now it's time to glue the clip on the backside of the flower. A little piece of fabric should help you ( see picture! ) and also it makes the clip less slippy :P If you use velvet, make sure that you put it "upside down" for the non-slippy-effect.

Explained in layers: backside of the clip -> piece of fabric -> glue on fabric -> front side of the clip -> some more glue on the clip itself -> flower. Gently press the fabric on the flower untill the glue works properly.
Make sure the clip is in the right direction ^^ I messed this up on my first clip xD

As you can see, I also made a scull earring ( and a button which is not photographed yet :P ).