Use the hat layer to create the limbs of the animatronics. It makes the skin very realistic and similar to that of the original design of the animatronic. Also, avoid pillow shading. Pillow shading is shading from a point of light source and it gets darker as you shade farther from said light source.
Also, try as much as you can, to match the colors of the skin to that of the animatronic. And if you're willing to put effort, make your own FNAF skin. And I mean own, like, a Lizard, T-rex, Shark, or anything similar. It helps with the originality thing.
