[mook]

It's not the default thing to do, but I've found that installing Homebrew under your home directory to work well. Everything's owned by that user, and there are no issues with shared machines (since other users don't see it at all). The downside is that casks (i.e. pre-built installers) might still end up installing things outside, but that would have been the same without Homebrew existing in the first place.