here's a quick tutorial that will teach you how to make a realistic render look like a cartoon.
1) Take the render that you want and open it in photoshop
2) duplicate the layer so now you have 2 layers with your render on each of them
3) on the top layer, go to Filter>Blur>Gaussain Blur and set it to 5-7 pixels depending on your preference.
4) set the top layer's blending mode to darken, and viola! you now have a more cartoonized image
(sorry that i didn't make any instructional pictures, i might post some later)
