Lift your fingers off the strings when you move to fret a new note. Those guitarists who fret sharply and have minimal contact with the strings between notes are the guitarists least likely to have squeaking during performances. Try practicing sharp, staccato notes to improve squeaks from your guitar strings when fretting notes.
Get new strings. Older strings have a greater tendency to squeak. Choose a type of string that is known for a low level of string squeak. If you know you plan on recording or performing soon, change the strings on your guitar a day or two before you plan to perform. This will allow them time to properly stretch and relax for better sound quality. If you do not have time to allow your strings to stretch naturally, you can stretch them manually by gently lifting each string with your finger and running your finger down the neck of the guitar under the strings for the length of the string. Repeat this process, stretching each string gently. Do not pull; simply let the pressure of your finger stretch the string. Do not press too hard; the stretching must be done gently.
Play with shorter strings. Shorter strings are more likely to have a clean sound and are less likely to squeak. If you need to change your key to play on the shorter springs, use a capo to change the key on your guitar by placing it on the 2nd or 3rd fret of your guitar. The shortened strings will be easier to control and less likely to cause squeaks or other foreign noises while playing.
Try a bottleneck or glass fret hammer. A bottleneck or glass fret hammer is a device you place over your fret finger. It is shaped like a tube, and a bottleneck is usually glass. The tube over your finger allows you to make smooth fret changes with minimal squeaking or other foreign sounds on your strings.
Wash your hands. Damp, clean hands have a tendency to squeak less than dry hands, and clean hands will give your guitar strings a longer, fuller life. Cleaning your strings is a good step to reducing string noise on a long-term basis.
Tune your guitar. A guitar that is in tune will resonate in-tune tones more loudly, making squeaking noises more audible in comparison. When a guitar is in tune, its vibrations of sound feed off of each other and produce a louder, more full sound that is less likely to allow string squeaks to be audible.
Play the guitar at a louder volume, and play the guitar a distance away from the microphone. If you have a problem with picking up string squeaks during recording, the best thing to do is play the guitar louder and place the microphone or microphone groups at a greater distance from the guitar so the microphone setup is more likely to pick up the desired guitar sounds than the undesired string squeaks. Be sure to be careful of phasing when placing your microphones.