Buttons come in three sizes (large, normal, small) and three types (primary, secondary, critical).
Two of these types (primary and critical) also have subtle versions in lighter shades to show actions that don’t draw as much attention.
Every screen needs a clear visual hierarchy of buttons and other interactive components.
Primary buttons are best for the single primary action on the screen.
Critical buttons work for destructive actions — actions users can’t take back.
All remaining actions can be Primary subtle buttons, Secondary buttons or Tertiary buttons — mostly ButtonLink or TextLink.
You don’t have to use every step of the hierarchy - you can skip a level if there’s no use for it in the context of a screen.