Check your string condition. If you have strings in terrible condition, it can affect the ability for your guitar to stay in tune. If your strings appear worn, try replacing them with fresh strings. Make sure the strings fit properly on the guitar. If your strings do not have enough slack around the tuning knobs it can cause your guitar to go easily out of tune.
Use a correct pitch reference. Perfect pitch references allow you to have guaranteed correct tuning. Some of the best references for tuning your guitar are a piano or digital source. Digital sources include software and digital hand-held tuners. If you don’t have a pitch reference, tuning by ear is still possible. The easiest way to correct ear tuning is by using octave references on the guitar. Put your finger on the fifth fret of each string. When you strike the note it should chime exactly with the string under it. This is the same for all strings except the B string, which is on the fourth fret.
Tighten the tuning pegs. In order to tune the guitar, you will have to use the tuning pegs at the end of the guitar neck. The tuning pegs tune the guitar by tightening and loosening the tension of the guitar strings. In order to make the pitch of the string higher, the tuning peg should tighten the string. In order to lower the pitch of the string, the tuning peg should loosen the string.
Cross-tune the strings. Start by tuning the first string on the guitar--this is the thickest string called the top E string. Once the first string is in tune with the pitch of E, tune the B string which is the second string from the bottom. Continue tuning each string in varying order; try to avoid tuning the strings one at a time from the top to bottom. When you cross-tune, it causes less tension on one spot of the neck and allows for easier tuning.
Choose your tuning. The standard tuning for a guitar is E-A-D-G-B-E. The order of the tuning is from thickest string to smallest string.
Re-tune your guitar. After tuning your guitar for the first time, try playing through for a few minutes. Check to see if the guitar has gone out of tune. If you find your guitar falling out of tune, you may need to replace the strings or simply tune the guitar a second time.