just really study the reference heavily, try and find skull imagery. Do anything to help yourself out, do a few doodles, grab a lump of plastercine if having somthing in real world helps, or even just use a load of primatives to build a rough skull to help you guide your model. With a cartoon piece you have to exhadurate the unique features. What can you find that makes a baby elephant look like a baby elephant, what features are the most important to highlight. Often, half of any art is strong planning and forethought, hold back for a bit and think about all the things you want to capture here, and how you can go about doing that. I think you need a stronger sense of what the result is going to be, realistic or stylised. If it is stylised then how, there are many ways to do a 'cartoony' elephant. Once you know that, its then the time to research and collect reference and then step back into maya.