Most of the basic information about guitar tuners and their characteristics can be found at the following Wikipedia page:

http://en.wikipedia.org/wiki/Electronic_tuner

 

Assuming you are familiar with the most common functions of a tuner, I would like to add the following tips:

1.  Although manual tuning of the guitar may not be necessary unless your tuner is lost or has a dead battery, it is always a good idea to know how to tune manually.  Information about this is easily available on the web as well. Remember, your octave relationships are the most reliable to your ear, even more so than unison. Harmonics (see 45. Harmonics for more info) can be a great assist in tuning, since you can turn the tuning heads while the note(s) are still ringing.

2. Most capos will cause one or more of the strings to rise slightly in pitch, especially the low E.  For this reason, I recommend tuning AFTER placing the capo on the guitar. Often a small tug of the lower strings (after the capo is applied) is enough to restore pitch in them.

3. Since note decay on the guitar is rapid, the tuner won’t read the pitch for long. It will begin to flutter, trying to read overtones and any competing tones. Constant playing of the note while tuning is key.

4. If you are using an open tuning, or any tuning which calls for one or more of the strings to be tuned lower than concert pitch, use as light a touch as possible when fretting. The lower the string pitch, the more the finger pressure of your fretting hand will tend to sharp (raise) the note. A soft touch of the fretting hand, heavier gauge strings, or both, will help.

 

© 2012 Jim Greenfield