Ideas

I quite like the idea of the skull being semi transparent - just need to see if it will work with type.

I am not sure if the fully opaque skull is a bit too bright - maybe another colour would work better?
Colour Experiments:

Looking at these, I think the application of colour takes away the fact it's a skull - in my opinion anyway. To me the shape just appears to be a coloured blob, but in white it is more clear that the shape is in fact a skull. If I place the final text on it may become visually more effective.

I do like the idea of just the white stroke, however to apply a text layer on top of this would make it difficult to see.

By applying a semi transparent layer with the stroke, this still looks effective, and I would be able to apply text without worrying about legibility. This is the same as the previous idea but this time I have added the stroke.