1) Think of an idea for a story.
Write down instances of conflict, and the scenarios that follow. Don’t make it too complicated or epic. This is not a feature-length, Hollywood box-office hit. Think of broad, simple conflicts, then focus on the details.
Once you have a general idea of a story, write a treatment of the story (broad overview of the story from beginning to end). Then, after looking over for kinks in the story, write the script of the story. Celtx is a good, free screenwriting software. Make sure you write the script in the proper format. Once completed with the script, ask someone you know to read it over. Chances are, they will catch some errors that you did not catch, since they are not biased toward the script.
2) Create a schedule for the rest of Pre-Production, Production, and Post-Production.
This will be your own personal guide to look to throughout the process of creating your film. In your schedule should include every little detail of what is happening when (when/where the actors need to be, what time is crew call, etc.). Having this information readily available will greatly help you when people will later ask questions about times and dates.
3) Find and finalize your location.
Depending on your script, find a location(s) that will be used to shoot the short on. Keep in mind of logistical questions that will come up when choosing a location (how long do have the location for, is there any electrical access to the location, will the crew be able to easily access the location, what permits if any are needed to use the location, etc.).
4) Find and build your crew.
Using the available mediums of information (craigslist, local Facebook groups, local filmmaking groups, colleges/universities), build a crew that will perform certain duties while on set. The basic positions include: Director (if you are not directing, which I highly recommend that you do Direct), Director of Photography, Sound Equipment Operators, Gaffer (lighting operator), Make-Up, Acting Coach, Clapper, and Production Assistants. Some of these jobs can be multi-tasked to one person, but if you have enough people to concentrate on their particular craft, the smoother it will be during production. Also, check to see if your crew members own/have access to the equipment needed for shooting. If they don’t, that’s something else you will have to figure out.
5) Find your actors
Using similar methods of finding your crew, find the actors needed according to your script. Use different channels to find your actors. Some include talent agencies, university/college theatre programs, craigslist, Facebook groups, etc. Have try-outs for the roles. This will give you some sort of idea of how much skill each actor has. Make sure to record every actor’s information (name, contact info). You might need them later.
6) Script-Reading Meeting
Once you have found some good options of actors to fill the roles in the script, have a script-reading with all the actors that will have any kind of speaking role. A script-reading is when all the actors read the script to see how the dialogue flows with the actors. You, along with anyone else that you deem vital to the production (Director, Producer, Writer, Acting Coach, etc.) should be present at the script-reading. Preferably have someone else read the narration of the script, so you can study the actors and how they interact with each other. Make plenty of notes of comments/possible changes. If you notice significant problems with an actor’s performance with dialogue, discuss the issue with the actors, so he/she can learn and fix the issue.