Film packages are created by film producers. Sometimes the producer of a film is also its writer, or its director, or its leading man. A film producer is just the guy who decides he is going to take responsibility for putting all the pieces of a film together, from the caterer to the camera man, from the leading man to the editor. The producer embodies and champions a film before it is made.
To create a good film package, a producer must simply decide that they alone are responsible for creating a profitable film.
Most unsuccessful film producers have a distribution plan that stops with "get a distribution deal" or "get a sales agent". Their marketing plan stops with "get our film into festivals."
A good producer explicitly and concretely nails down exactly how a film funder is going to get their money back. Producers prove, through their package, that they have created the relationships, skills and information required to make a film make money.