1. Get standard banjo tuning: For a 5-string banjo, the standard tuning is G4-D3-G3-B3-D4, while for a 4-string banjo, it's G4-D3-G3-D4.
2. Attach the guitar tuner: Clip the guitar tuner onto the banjo's 5th string (or 4th string for a 4-string banjo).
3. Tune the 5th (or 4th) string: Turn the tuning peg of the 5th (or 4th) string until the tuner displays a G4 note.
4. Tune the other strings: Tune the other strings by following the standard banjo tuning mentioned earlier.
5. Double-check: Play each string to ensure it sounds at the desired pitch. If needed, adjust the tuning until the notes are accurate.
Remember that different tunings may be used depending on the style of music being played. It's always a good idea to refer to the specific tuning requirements for your banjo and the musical piece you're playing.