Use a reference pitch from a piano, pitch pipe, tuning fork, or another tuned instrument
Tune the low E string to the reference pitch
Tune the A string by fretting the low E string at the 5th fret and matching it to the open A string
Tune the D string by fretting the A string at the 5th fret and matching it to the open D string
Tune the G string by fretting the D string at the 5th fret and matching it to the open G string
Tune the B string by fretting the G string at the 4th fret and matching it to the open B string
Tune the high E string by fretting the B string at the 5th fret and matching it to the open high E string
Check the octave between the low E and high E strings
Play harmonics at the 5th and 7th frets to compare strings
Listen for beating and adjust until the sound is steady
Recheck all strings after tuning because adjusting one string affects the others
Use natural harmonics at the 12th fret to compare octaves
Tune by ear against songs or recordings in standard tuning
Use the 5th-fret method repeatedly until the guitar sounds in tune across all strings