depending on the company culture
the best way is to have an alternative plan and tender your resignation, if they reall want you, they will counter-offer; if they don't counter-offer, you can also move to another company.
There is no 'proper' or standard way to ask for a raise or salary increase.
It's not something that people are trained to do, and little is written about it. People use various approaches: they can write; discuss informally; discuss with colleagues and hope the boss gets to hear; they drop hints to test the water; they ask the boss politely; demand firmly; go over the boss's head, or maybe even threaten to resign, secure another job offer, or simply resign.