I've got a little series of Halloween themed tutorials for you. Most of them are free-hand designs, which means they're not great but I do the best I can with my limited artistic skills. I had planned to start working on these tutorials sooner, but ended up not getting to it till now. So, I did all of them in one day simply because if I didn't do them all at once I probably would not have gotten all of them done. As such, I only did each design on one nail rather than in a full manicure. I did it this way to both save time and to save my nails and cuticles from having to be subjected to too much nail polish remover in one sitting. I have been having some issues with my camera lately too so I apologize that the pictures are not as clear as they should be.
For this design, start with a light green shade of nail polish.
Using a black nail art polish, make a stripe of black along the bottom edge of your nail (by the cuticle).
Using the nail art polish brush or a toothpick (whichever is easier for you) make some short downward strokes from the black polish. This makes your monster's hair.
Now make eyes. I do this by first making white dots, then placing smaller black dots on the white.
Next I add a small curved line for the nose. You can make the nose however you like.
Now make a line for the mouth. I've made a sort of wavy line, but you could just do a straight line if you prefer.
And finally add some vertical stripes across the mouth to make "stitches".
Let it dry enough that it will not smear when you add top coat.