Does anyone know how to write a design brief?

I’ve never used a design brief before, but I think it would be prudent to use one on my next project. I’ve found a lot of resources of what consists of a good design brief, but I don’t know how to actually write one. Is it bullet points/lists? I wouldn’t even know the first questions to ask; in other words, a complete newbie to this realm of work. Does anyone have a sample they’d mind sharing? Thanks!