`-Wall -Werror -Wextra` is the first thing to add to any project's cpp flags. And then selectively -Wno-whatever the stuff you don't really care about or is too

`-Wall -Werror -Wextra` is the first thing to add to any project's cpp flags. And then selectively -Wno-whatever the stuff you don't really care about or is too annoying to go fix if it's an existing codebase