Plug the guitar into a tuner or use a clip-on tuner
Tune the thickest string to E
Tune the next string to A
Tune the next string to D
Tune the next string to G
Tune the next string to B
Tune the thinnest string to E
Turn the tuning peg slowly
Tighten the string to raise the pitch
Loosen the string to lower the pitch
Recheck each string after tuning
Repeat until all strings are in tune
Stretch the strings gently and retune if needed
Check tuning again after playing for a few minutes