How does one go about rendering a game completely toon shaded?

I absolutley love the toon shading style and i feel that it has not been explored properly yet.That is why i want to deal with two types of game styles in my game studio.Very realistic or really well toon shaded (think borderlands).I want to learn about toon shading and (if possible) realistic hd textures.But how do i go about it? Do i use textures that are coloured like cartoons? Do i use some add on/unity extension?

Thank you for your time!
You would really be helping me out.

Unity has ToonShading package (you can import that by right clicking on project panel). By using shaders from that package on all modesl will give toon look for your game.