Mark a sheet of parchment paper with a circle about the size of the top of your cake. You'll use this to lay-out the dragon prior to placement on the cake.
Take a paper plate or cardboard and cut out a shape the approximate size you want the body section of the dragon to be. This will be used as a temporary base to hold your dragon body while you're covering it with the icing/fondant. Lay it out on your circle to ensure it fits nicely. You can place your head in the circle as well, and note where you'd like the tail to go.
Now the fun part! Take a good sized handful of the cake, and pack it lightly into an oblong ball, using your base shape as a guide (Note, pictured here is the size of the smaller mini-dragon)