Making more realistic lighting and quality

I am trying to create realistic lighting in my new movie. I want to make my movie look clear like films like ratatouille and other pixar style films. Is there a way to do this?

Start by studying movie lighting in the real world. Just do a web search for film and video lighting. The most basic concept is the three point scheme - key, fill and back. Figure out what this means, then study quality still photography and movies. You will begin to see where the light is coming from just by looking at the image. When that becomes second nature, you will have no problem picking the type of light and placing it in the 3D world to obtain the right effect.

http://warpedspace.org/lightingT/part1.htm

http://www.3drender.com/light/index.html