Turn on the guitar tuner
Set the tuner to guitar mode if needed
Choose standard tuning unless you want a different tuning
Start with the low E string
Pluck the string one at a time
Watch the tuner display
Tighten the string if the note is flat
Loosen the string if the note is sharp
Tune the string until the tuner shows the correct note
Repeat for the A string
Repeat for the D string
Repeat for the G string
Repeat for the B string
Repeat for the high E string
Check each string again after tuning all strings
Retune any string that changed
Make small adjustments until all strings are in tune