How To Tune a 12 String Guitar
Tuning a 12 string guitar is a simple matter once you learn how. At first those 6 extra tuning pegs can seem intimidating. If you know how to tune a 6 string then you're already half way there. Both instruments are usually tuned to the same E tuning. The only difference is that the 12 string has pairs of same note strings instead of 6 single ones. Some string pairs are tuned to the same note while others are in different octaves.
The first thing you'll need is a reference note to tune your instrument to. Pitch pipes and tuning forks are good cheap options. There is also a variety of electronic tuners that are especially helpful for acoustic-electric 12 strings. You can find a number of websites that also give you a reference tone to tune your guitar to.
Once you have your pitch to tune to, you can go about this in one of two ways. You can tune each string to a reference note, or tune the low E string and tune the rest to it. You can tune a guitar to itself once you have the low E in tune by holding that string down on the 5th fret and tuning the next open string to it. Every note played on the 5th fret should be the note of the next open string going down. The only exception is the G string which is the 4th one down while holding the guitar in playing position. You'll need to hold the note at the 4th fret to tune the next open string which is B, then go back to the 5th fret for the next string. When you hold your guitar in playing position the thickest gauge string at the top is the low E. Going down from there and working your way to the thinnest string, the notes are A, D, G, B, and the high E.
On a 12 string guitar these are tuned the same but in pairs. The low E's are an octave apart with the lighter gauge string being the higher octave. A strings gauge is it's thickness, so when I refer to a lighter gauge it means the thinner string. Follow this same pattern for the A,D, and G string pairs. The E and B notes are tuned in unison and then you're all done and ready to play.