Standard six-string guitar tuning from the lowest-pitched string to the highest is E A D G B E. Learning that order makes any chromatic tuner much easier to use.
Tune one string at a time
Pluck an open string and wait for the display to stabilize. If it is far from the target, turn the tuning peg in small steps and check again before continuing.
Understand cents
The note name tells you the nearest pitch class and the cents value shows how far you are from its center. Negative values are flat and positive values are sharp.
Avoid the wrong octave
If tension keeps increasing and the string still does not seem right, stop. You may be aiming at the correct note name in the wrong octave. Comparing with a known reference can prevent a broken string.
Check again at the end
Changing one string slightly affects overall instrument tension, especially on floating bridges. After all six strings are close, make one final pass.
Before practice starts
Tune after the instrument has spent a few minutes in the room, especially after a temperature change. New strings also stretch and often need several corrections during their first hours of use.
After open strings are in tune, play a familiar chord. If some areas of the neck remain clearly out of tune, the issue may involve intonation, old strings or setup rather than the tuning pegs alone.