There are lots of ways to write variable names when programming. This is the list of ones I find myself using.
I’ve been using PHP CodeSniffer to help me following coding standards. The WordPress Coding Standards are a great resource and the basis of the rules I follow. I have made a few modifications based on my personal preferences.
The editorconfig project provides a powerful tool for standardizing the general coding standards used in a project, specifically in regards to: indent_style, indent_size, end_of_line, charset, trim_trailing_whitespace, and insert_final_newline.