Snake versus Camel case is pretty much a personal thing and tends toward religious fervor. prefix and postfix annotations of any sort are generally much less important than getting the identifier name "right". Often prefixes or postfix annotations mess up good names and add clutter. Where annotations are used they are often an institutional convention or coding practice.

As a personal thing I use a k prefix for global constants and that's about the only annotation I use in Perl. In other languages (C++ mostly) I use g as a prefix for global static variables - those almost never leak out of a compilation unit. Most compilers for languages that care are pretty good at reporting type mismatches so there's no point decoration variable names to indicate the variable's type - that just adds clutter and slows down understanding. Good variable names are essential. Decorations generally just distract attention from the work being done.