To know how to Tune a Guitar ? Tuning a guitar is essential for clear, accurate sound. Start by using a tuner—either digital, clip-on, or a tuning app. Standard tuning from the thickest to the thinnest string is E-A-D-G-B-E. Pluck each string one at a time and adjust the tuning pegs until the tuner shows the correct note. Turn the peg slowly: clockwise to lower the pitch, counterclockwise to raise it. Always tune up to the note for better stability. If tuning by ear, use a reference pitch or another tuned instrument.