Learn the terminology associated with Gregorian chant. Common terms include "final," the last note of a chant; "dominant," a particular chant's reciting tone, which is repeated frequently within the chant; and "mode," which indicates the collection of pitches used in a particular chant.
Practice the modes of Gregorian chant. The most important modes to know are the Dorian, Phyrgian, Lydian and Mioxlydian modes (see Resources). Learn the modal scales associated with each mode and practice singing each mode.
Learn to read Gregorian chant notation, called square notation, using the tutorial from Cecelia Schola (see Resources). If you have a piano, check your pitch by playing while you sing.
Join a choir that sings Gregorian chant. Singing with a group will help you improve your reading and singing skills quickly (see Resources).