Tune the 12-string guitar in pairs, with each pair sharing the same note name
Tune the lower four courses to standard guitar tuning: E, A, D, G
Tune the upper two courses to standard guitar tuning: B, E
Tune the octave strings on the lower four courses one octave higher than their matching main strings
Tune the B and high E courses in unison, with both strings tuned to the same pitch
Use a chromatic tuner for each string pair
Start with the lowest E course and work up to the highest E course
Tune the main string first, then match the paired string
Check each course by plucking both strings together
Retune after all six courses are set
Repeat the tuning check until all pairs are in tune
Verify the final tuning as E E, A A, D D, G G, B B, E E