A good option for marking your queens. For the beginner the way to go.   Use a Queen Marking Cage to simply hold your queen still on top of the comb and mark her thorax with the pen through the mesh of the cage.

The standard international colours are red (for years ending in 3 and 8), yellow (for years ending in 2 and 7), white (for years ending in 1 and 6), blue (for years ending 0 or 5) and green (for years ending in 4 and 9).

The international colour standards are really only needed if you plan on selling your queens.  For most who use their own queens, any colour will do as long as you know which colour you used in which year.  Some beekeepers may want to use one colour for autumn raised queens and another for spring/summer raised queens.  It is up to you.