I might be already exposing myself as an emacs user, but I think Lisp naming convention is pretty reasonable. I use it in other languages as far as their language rules allow me

• if a variable or function is a predicate (as in if it tests if something is true or not), append p or _p/-p

• variables and functions both have lisp case variable-name-here. Sub for _ in languages that dont allow - in names

• unused or unexposed variables are prefixed _ .

• top level packages get naming rights. So if I'm making cool-package then variables or functions that are specific to it are cool-package-variable (especially if it is exposed to other packages). cool-package/variable is also good if allowed.

• otherwise, separate namespaces with /. So there's main-function and my/main-function. If / is reserved, then I assume the language has a way of segmenting namespaces already and just default to that since _ or - would get ambiguous here.

See the rest here: https://github.com/bbatsov/emacs-lisp-style-guide