Step 1: The head
Step 2: Facial features
Step 3: 3d model and Pumpkin
http://www.123dapp.com/smb-123D_Design/genki-pumpkin/1720226 Genki pumpkin
And now the steps for the pumpkin.
Draw a large circle at the bottom of the head and extrude it almost all the way through. Then extrude the mouth, nose and mouth.