Find a camera that shoots video. This could be a normal digital camera that also takes video, a dedicated video camera, a DSLR, iPad or your iPhone or android. It doesn't have to be flash, just get hold of some kind of video camera. Keep in mind when choosing though that depending on what you choose you may have to think about storage. An iPhone won't hold as much video files as you might like. You don't have to own the camera, you could borrow one from a friend or if they don't trust you, ask them to film for you. You can buy low quality camcorders now for as little as £20 these days and that is fine to start with. You just need a machine to record video to get started.
Come up with a short, simple screenplay. Try and keep it to 2 minutes (that would be roughly about 2-3 pages of screenplay) You can follow my writing exercise on how to write a simple character and plot for your short film. You can also use things that have happened to you or your family. You can ever find a story you like and direct that. Just make sure your story is short and simple with a strong character who wants something and goes on a journey to achieve it. There is a great book called Writing Short Films that I used when I started out. One of the exercises in there helped me write Piece of Cake, my first short film. Remember that your first short film's aim is to practise making a short film. So don't go crazy thinking up a complicated, long script. It could be something as simple as a man who wants to buy the last apple in the shop but another man has the same idea. What happens? Do they fight it out? Does he let him buy it but then go after it another way? Is there a twist?
Write your script. Write it down. Even if there is no dialogue, just make an outline of what happens, purely for your benefit.
Think about how you want to shoot your script. Low angles? High angles? Moving shots? Dark, light, colourful? How will you tell certain parts of the story with certain shots and styles? Do some sketches. Make decisions now and note them down.
Enlist your actors. I would use friends and family if you don't know any actors or are finding it hard to find semi-professional actors. You may have had someone you know in mind when writing your script in which case they will fit the role. When choosing friends or family to act in your film, make sure they are people who are willing to listen to your direction and who aren't camera shy (or who love you enough to overcome their shy-ness) If you manage to enlist the help of professional or semi-professional actors in your film, don't be so intimidated or grateful that you forget to direct. Don't be afraid to be bossy (in a nice way). This is you directing. Get what you want out of these actors, keep asking until you get the take you want. I have made the mistake several times in the past of being so grateful to actors for just turning up, that I am afraid to hurt their feelings by making them work hard or asking them to do a take again because the first one was terrible. Don't be rude, just be persistant. You can find actors who are willing to act for free on Casting Call Pro as long as you write a great casting call really selling your project, but to be honest, you tend to find actors through other filmmakers and connections you make through filmmaking.
Shoot your film. Looking at the ideas and notes you made when thinking about your script, go through your scenes and film them in the order that is easiest to film. You don't have to shoot your film in the order things happen. For example, if you have 5 scenes that need to happen in the kitchen but are at different times in the story, film them all in one go in the kitchen. The reason for doing this is it makes it easier because you don't have to change equipment round 5 times AND the continuity of the scene will be controlled. If you film one scene in the kitchen, then go and film 5 other scenes elsewhere, someone might use the kitchen while you're filming and change how things were. It's also quicker and stops you dragging out the shoot time which can make everyone tired and grumpy. Don't rush. Get the scenes you want how you want them. This has been one of my biggest learning curves. I have spent many hours crying over footage because I rushed things, worried about people's time and money, to come home and realise I didn't get what I want. Take your time. Refer to your script throughout shooting. Have someone there to help you remember to get transition shots (shots that carry you from one scene to another) and to help you remember important small scenes or cutaways. Get several different angles of the same scene. You won't regret it. There are some great books to help you think about shots when filming. Film Directing Shot by Shot and Master Shots and The Filmmaker's Eye are some filmmaking books I live by when storyboarding and planning scenes.
At this point I would like to mention sound. You may have a very simple camera with a built-in microphone so sound quality may be low. Don't worry. You don't need an expensive microphone. What you do need to do is overcome the quality problem by making sure you get good sound. Make sure everyone is quiet on set if your mic doesn't pick up well. Tell the actors to speak loudly if you think you're not picking up sound well. Wear headphones while filming to make sure you're getting relatively good sound. If you don't have a great sound setup, consider not shooting that scene in a noisy cafe with dialogue - change things around to suit your situation. You could also plan to dub certain scenes later in the editing process. If you do that, plan for it. Keep it mind when shooting.
Edit your film. If you're just starting out you probably won't have dedicated editing software just yet. That's ok. All that means is you have to work a little harder to edit your film. When I was playing around with filmmaking age 10, I had to capture tape onto the computer and then somehow edit it together in the form of slides in Powerpoint. So each scene was a video clip on a Powerpoint slide which I then played together and recorded back onto VHS. If you are age 13-14 you may have to google most of those words. What I'm saying is that I did not have Final Cut Pro or Premiere Pro to edit with in the beginning but I found a way to cut together my film. You can also, if you're really stuck, edit your film in camera. This means you cut while filming at the right point so that your film plays back chronologically in the camera. This also means you will have to shoot in sequence and you can't make mistakes. Not a wonderful method but something to try if you don't have editing software and you want to see how your film looks or play it back to friends through your camera.
Screen your film. I would definitely invite your friends and family and cast and crew to come over and watch your film before you lock the edit. Don't be upset by criticism. If someone says it's boring, that probably means the edit is too long, cut it back a bit. If someone says the acting is bad, it might be that you haven't got the message across in the scene and you may be able to fix this with music and clever editing. Listen to feedback and if needed, re-edit. Then watch it again with a different audience. Have a movie night at your house with popcorn. Watch people watching your film, it's a great way to see how your production is going down. Are their eyes locked on the screen? Or are they yawning? It can tell you a lot about your filmmaking depending on when your audience gets bored and it can make you think about why that is. Once you've had an initial screening it's time to share your film with the world. There are so many outlets now. Put it on YouTube, Vimeo, Facebook, Twitter etc., Research local film festivals or local film groups and ask if they might screen your film at one of their film nights. Send it out to your email contacts.
Learn from this film and start on your next one. Using all your knowledge, make your next film but this time remember all the mistakes and potholes and work your way around them. Maybe next time try a completely different style or story. Drive your actors harder. Make it more exciting. Edit it tighter. You will gain a feel for what to do better next time and I would strongly advise writing down all the feedback you get, good and bad, keep it in a special notebook and refer back to it on each project. This is how you will learn and become better at your craft.