First of all paint your nails black, I used Barry M - Black for this design
Next, using the brush in the nail varnish, paint a squoval shape on the corner of your nail, it's best to use an opaque colour for this if you're using a black background, I used Barry M - Blueberry
Next, using a small dotting tool make the ears and arms (Don't worry about it being completely even as the top coat will even it out later)
Once all the blue is dry, take a large dotting tool to create the eyes using white nail varnish (I used Rimmel). Then using the thinnest dotting tool you have, create the nose using red nail varnish (I used Barry M) and using the same dotting tool create the pupils of the eyes using black.
Then, using a thin paintbrush, or (if you wish) the dotting tool again, paint a thin black line for the mouth and add small white dots for the teeth using the same brush/tool.
Then finish off with a topcoat and you're done, you can also do this with other colours and body shapes as in the first picture using a similar technique.
I'm sorry it's a bit rushed towards the end, I didn't have much time, but I hope this was helpful!