My kids all used spiral bound notebooks when they were in middle and high school and they always had four or five books every year that had a left over portions of the book that they didn't use. I took their old notebooks and used them to keep notes about the item's model and serial numbers, symptoms, disassembly notes, hand drawn schematics, test points, voltages and current readings, what parts were bad ,etc, etc when I made repairs. Then about once per year I would go through the note books and tear out the (pre-preforated) pages and put them into three rings binders sorted by equipment brand and model numbers.
Using a camera sounds like a good idea but it takes up a lot of time and then you have to keep up with the memory cards, etc so in the end it was just quicker and easier to keep notes in a notebook. OTOH if you plan on posting your repair videos on U-tube or somewhere then a camera is a necessity. But if that's the case, then you need to get a good one and mount it on some kind of stand and add the necessary lights, back drops, etc to your work bench. I'm sure that you've already seen some of the very amateurish looking videos on U-tube where someone tried to do a repair while holding their camera in one hand at the same time!