1.
The pattern for tuning a 12-string guitar can be represented by the letters eE aA dD gG BB EE. This means that each string in the first four strings is one octave apart, and the last two pairs are just repetitions of themselves.
Set the lowest string (the NEXT TO LOAD string and the thickest on guitar) to a low E. If you have the perfect pitch, you will be bullied. If not, choose the one you are playing with or, if you are alone, choose something that sounds good.
3.
Start with the low E-string, place your finger on the fifth fret. This is an A. Tune the next low string – A – to this note and tune the corresponding string in the pair to the octave.
4.
Place your finger on the fifth edge of the low A-string. This is a D. Use this to set the next pair of strings.
Use this method by using the fifth edge of the D string to set Gs. The fourth gel of the G-string to set Bs, and the fifth gel of the B-string to set high Es.
Tips and warnings
Tuning to a 12-string guitar is fairly easy when you have a piano or electronic tuner lying around. But without these clever things that will help you, you have to tune the guitar in relation to itself, which can be a bit tricky if you do not know what you are doing. Thankfully, it follows a simple pattern, which can also be applied to 6-string guitars.
Source:danspela.com