That’s a pretty broad question but here’s my advice:
Do as much as you can before hand. The worst thing in the world is showing up to shoot a video and not knowing exactly what you want. A documentary cannot always be entirely scripted so write down ideas you want to inbclude. Get a basic outline down on paper. Write down any shots that you want to get. Otherwise, when it comes time to shoot, you will forget alot of things you wanted to do.
Call or visit the police/fire dept and let them know what you are doing. I’m sure they will be happy to help and will probably have some ideas for things to include! Schedule times to go shoot the video. Get other people involved too! No doubt there are others your age who would love to help and might have something good to contribute. Just make sure you stick with the vision YOU have. Sometimes when others are involved, they want to make it their video. While they might have some good ideas, it’s your video so don’t lose your direction.
Make sure you have the equipment you need all ready to go. I assume you have some equipment but make sure you use an external microphone for interviews etc. even if it’s a cheap one. If you need equipment, your school may have stuff they can let you use. Theres alot of equipment you can make on your own too! I’ve made a track dolly, a microphone boom, and I’m considering building a teleprompter too! (I don’t use this stuff for weddings because it’s pretty ugly but it is very functional).
Any specific questions you have just ask!
