While creating a film one has to bear in mind two major factors :
Aesthetically - Your audience category
Technically - The medium you are primarily going to use to reach to your audience.
Aesthetically -Are the audience teenagers, adults, elderly and from which part of the planet earth? The film message should be designed politically correct for your target audience. It should not hurt social and religious beliefs of your target. Once I was making an animation film for Discovery's online channel, unitedstreaming.com for primary school children. The authorities asked me to use characters, such as pigs, bears, and cats as characters, which the children were positively familiar with, and which would be politically correct association in their country's educational environment. Therefore designing the characters and their environment is very important - positive-negative, black & white, good & evil have different meaning/nuances to situations being portrayed to a target audience.
Technically - What would be your primary mode of exhibiting the film, theatrical, satellite, online or mobile? If you are making a feature film for the big screen and a have full length 2/3 hours canvas to tell your story, then you have to think larger than life in all aspects, directing and producing the film. On the other hand, if you are making a 30 second advert for the small screen or the mobile your challenge is tougher- you have to package your story in those 30 seconds and convey your message completely.
Last but not least, in a live action film if you are using animations use it to build around missing scenes/characters where live action or human actors cannot replicate that which can be conveyed through animation. I was asked to make CG animations for a live action Martin Luther Junior ' documentary for a scene where an elderly colored lady is humiliated in a public bus. They could not find 'live references’. Therefore they asked me to appropriately animate the scene.
To sum it up your film has to look realistic and complete in all levels of production design before you get into 'Lights, Camera, Action!"