Harry Potter: How Does a Wizard Become a Death Eater?

While many groups, organizations, and alliances form part of the extensive Harry Potter lore, none is as infamous as the Death Eaters, known for their allegiance to Lord Voldemort and their use of dark magic. Although there are many shared characteristics amongst Death Eaters, mainly their loyalty to the Dark Lord, there are wizards and witches who, despite being loyal to him, aren’t Death Eaters, such as Narcissa Malfoy. So, how exactly does an ordinary wizard get to join their ranks?