How to of the day! (For chief31, in case he restrings the air guitar he got on ebay!)
How to Tune a Guitar
If you want to be a guitar god, you need to have a properly tuned guitar. While there are electric tuners (or band assistants) to make the job effortless, a good musician must know how to tune his own instrument in a pinch. So, here's how to tune a 6-string guitar with the standard tuning method.  Steps
Know which note each string on the guitar plays.
Note that there are two E strings on the guitar. The thickest string is the bottom E (or low E) and the thinnest string is the top E (or high E).
Know which tuning keys correspond with which strings.
Find a way to listen to an E note. This can be done using a (properly tuned) piano, a pitch pipe, or a recorded E note found on the web as a .wav or .mp3 file.
- Put the guitar on your lap in a comfortable playing position.
- Plucking bottom E string
Pluck the bottom E string (the thickest string) while listening to the E note from some other sound source (i.e. piano, pitch pipe). The bottom E string is good to begin with because its thickness makes it less likely to detune.
- Tuning bottom E string
Turn the tuning key for the bottom E string until your guitar's bottom E string sounds the same as the known E note. Turning the key so that it tightens the string will make the pitch higher, while loosening the string will make the pitch lower.
When the string is slightly out of tune, the E from the guitar will combine with the E from the sound source (i.e. piano), and cause the sound to "waver" in pitch. As you tighten the guitar string, you should hear this wavering slow down; the two strings are in tune if the wavering has stopped. If you go too far, the wavering will increase again.
- Fifth-fretted bottom E string
Push down on the fifth fret of the bottom E string that you just tuned and pluck the string. This will be referred to as the fifth-fretted bottom E string.
- Plucking A string
Pluck the A string and compare it to the sound of the fifth-fretted bottom E string. Pluck the two strings in succession and then simultaneously.
- Tuning A string
Turn the tuning key for the A string until it sounds the same as the fifth-fretted bottom E string.
- Fifth-fretted A string
Pluck the D string and compare it to the sound of the fifth-fretted A string. Pluck the two strings in succession and then simultaneously.
- Tune the D string to the fifth-fretted A string.
- Fifth-fretted D string
Pluck the G string and compare it to the sound of the fifth-fretted D string. Pluck the two strings in succession and then simultaneously.
- Tuning G string
Tune the G string to the fifth-fretted D string.
- Fourth-fretted G string
Pluck the B string and compare it to the sound of the fourth-fretted G string. Pluck the two strings in succession and then simultaneously.
- Tuning B string
Tune the B string to the fourth-fretted G string. Note that this is the only time the fourth fret is used.
- Fifth-fretted B string
Pluck the top E string and compare it to the sound of the fifth-fretted B string. Pluck the two strings in succession and then simultaneously.
- Tuning top E string
Tune the top E string to the fifth-fretted B string. Be very careful when tightening this string as it can break easily.
- Tune your guitar every time you use it. Playing can make your guitar go out of tune, especially if you have a cheap guitar or old, cheap strings or if you use tremolo a lot.
- If you are tuning a bass guitar, the layout is the same. The difference is a bass guitar doesn't have a B and high E string.
- You will find it easier to tune each string if you loosen the string to flatten the note, then increase the tension to come up to pitch. Some of the strings have a tendency to "stick" where they slide over the nut, and will be in tune until they suddenly slip flat. By coming up to pitch, this tendency is avoided. You can also lubricate the slot in the nut with graphite (pencil lead) and it will help to avoid sticking during tuning.
- If you don't have access to a piano, keyboard, or tuner, pick up your phone! In the US at least, standard dial tone is an F.
- After tuning, strum open major chords in the five common chord forms (C, F, G, A, and D). Make sure they sound right (no dissonance, or wavering). A guitar can seem in tune using the method described above, but if the intonation is not set up quite right the guitar won't sound quite right. You may need to make some minor adjustments to ensure that chords sound right.
- After tuning, make sure the G string and the G at the eighth fret of the B string sound the same (other than being an octave apart, obviously). These two notes being slightly out of tune is a common problem and will make chords sound very bad. It's better to have the E and B strings a *little* bit flat relative to the low E string than to have the G string sound out of tune with the E and B strings. This problem has to do with the way guitars are designed but is exacerbated by bad intonation.
- Tune your guitar to concert pitch. Tuning it flat can have a negative subconscious effect on your listeners. Most people have a sense of absolute pitch whether they recognize it or not. Tuning your guitar flat will make something sound not quite right to your listeners. Besides, playing trains your ears. Train them right!
- If you have a Floyd Rose or other floating bridge, and you have a locking nut, than the little twisty knobs at the bottom tune your guitar. Clockwise is up, and counter-clockwise is down. than again, if you have a Floyd Rose you are probably proficient enough to not be looking at this page.
- This is not the case with all guitars. Guitars that have "fanned frets" use different scale lengths for each string and are called Novax guitars.
- If you begin tuning with the higher E string [the thinnest string on the guitar] instead of the thicker, lower E string, you're less likely to break a string in tuning, especially if your strings are old or the guitar has not been tuned in a while. Be sure to keep your face away from the fretboard to avoid being injured by broken strings!