Are you using Poser?

Have you tried the "sketch render" option?

What application is your render coming from?

Pretty much all applications have some toon shader.

They're not perfect, but they get you started.

In photoshop itself, you'll do better doing some basic work by hand.

First, identify a style you want to match. People often say "i want it to look like a cartoon" -- without really knowing what it is that they want.Is it a halftone (dots) or something continuous?