A protagonist wants to make a documentary

Really I think the best thing you can do is just see if the local library or Amazon has any books on filmaking, or especially filmmakers for students. There's probably a "Dummies" book as well.

Her equipment depends on her finances and resources. Is she paying this out of pocket? Is she taking a film class in high school or college that would give her access to equipment?

Why would an 18 year old make a documentary on herself? What makes her special? That would affect how she approaches it. Is she chronicling some special activity she does or some life event she's going through? That would effect how she tells the story which would effect how she shoots the scenes.

What is the purpose of the documentary as well? Is it for a school project? An entry for a competition? A project to try to get her into a film school? Just something she's doing an a lark? That will help you better understand her mindset and the relative importance she places on it.

Is she doing everything herself, or is she part of a team? As a one person show it's harder to get good lighting, good recording, good sound, etc, then if you have a crew. Even a small crew.

With good quality video cameras being so relatively inexpensive (compared to movie cameras) and not having to pay for film and film processing making a documentary is much easier than in the past. Video editing software is much more available now and you can get pro quality or near pro quality editing software for an affordable price. It does take some skill to use and you have to learn the software but there are books and video tutorials to help.

For equipment, if she's just doing it on a lark there are consumer level video cameras for about $500 that will shoot HD quality 1080 video. That's fine for YouTube or local screenings. Stuff shot for wider release is typically done on higher end equipment. Even stepping up to a $1500 camera gives you better equipment. It goes up from there...

The hardest thing, and a thing that is often overlooked, is getting good audio. If you want to show that she is still learning and doesn't yet understand everything have her record her audio with her camera. Even with an external mic it's still probably not going to be as good as an audio track recording separately into a dedicated audio recorder with a better quality mic.

Heck, even without buying books there are enough websites on movie making that a few hours research should turn up a ton of info plus some dedicated forums for amateur film makers where you could read what they talk about and ask specific questions.

Equipment: iPhone?

The Oscar-nominated documentary filmed on an iPhone

‘Framed’, A Beautiful Short Film Shot Entirely on an iPhone 4S

I was thinking what Bing posted. These days there are all sorts of things that someone could use for a documentary. I wondered that for a short story and learned that there are plenty of low price video cameras out there that are better than low end movie cameras.

Even newer SLRs are capable of shooting HD video. I don't have a link right now, but check out Canon DSLR HD video for examples.

Basically, equipment doesn't need to be expensive, high end stuff.

As the others have said, high-end cameras aren't necessary. There are plenty of docs and indie films shot on cheap cameras, including iphones mounted with special lenses and mics.

Good audio is very important, but it's something that a lot of amateurs don't consider.

Depending on the documentary set up (ie, is it mainly talking heads against a background, or is the camera handheld following the action) your character will want to consider lighting. For a talking head interview set up, they could get by with natural light and maybe a cheap light or two (even a china ball light from Ikea) or a bounce board. If your camera is hand-held and following the action as it happens, there will likely be moments where your subject is too back-lit and your camera operator would ask to swivel the action (if possible) so that the light from a window, etc, isn't behind the subject.

When I was in high school there were a few "prosumer" magazines I read, and they often ran articles like "How to shoot a short film for $500" - if you can find a few of those types of articles online it would probably be very helpful.

I don't know if you're going to dip into post production/editing at all, but while your protagonist might just use a cheap/free program like imovie, it's more than likely they'd pay to get something a little better. Organizing hours of unfocused footage is difficult for a beginning, and imovie and programs like that don't offer the right tools for it.

Having done a bit of video myself, plus seen professionals at it I second (third?) the audio.

Professionals have the big furry hamsters on the microphone to remove wind noise. Video microphones - that is the little holes in a camera pick up all sorts of wind noise. Professional sound guys have dials on their equipment, with needles flicking across it, showing them sound level of background and then when someone speaks so they can check it is loud enough but not too loud.
Could be the first mistake she makes, has to go back and re-do - thank you so much for the interview last week, can we do it again.....

Agree with lots here. Nothing fancy needed but sound can make all the difference in the world. Handheld is fine. No tripod needed imo as it can make a scene stiff.

Remember to copy, back-up, store originals. ALWAYS. EVERY. SINGLE. DAY. This is crucial.

Be willing to turn on a dime, catch the scene behind the scene. This is where magic can come in, take your film to another level. A documentary doesn't have to stick to a script and as a matter of fact the more unscripted, the more authentic.

Plus more often than not, a documentary is created in the editing room after hours and hours of dull and dry footage. And if you're doc's shot on the fly, the story will be created in the editing process and this is watching grass grow and a lot of sitting and tweaking and backing up and flash forward and stop, retrace, stop, freeze frame and so forth.

Good luck.

Gringa