Banjo purists are dismissive of the 6 string banjo. The criticism concerns the ambiguity of the instrument. On the one hand, it seems to fit into the banjo family but, on the other hand, it just as easily fits into the guitar family. Its six strings are tuned like a guitar in standard tuning. This makes the 6 string banjo very different from the 5 string banjo used in bluegrass and the mountain banjos used in old time music. It is more similar to the 4 string tenor banjo used in early New Orleans jazz and ragtime music. The tenor banjo is primarily a rhythm instrument used to play chords. If you are interested in the six string banjo learn how to incorporate banjo techniques into your playing rather than simply playing it like a guitar.
Tune the banjo to standard guitar tuning. Clip an acoustic guitar tuner to the headstock of the banjo and tune the strings to E A D G B D, starting with the lowest string.
Learn four string jazz guitar chords. Jazz guitarists usually avoid playing chords on all six strings. Jazz rhythm guitar focuses on the E A D and G strings. Rhythmic intensity and drive is achieved by moving the chords up and down the fretboard using different inversions of the chord. The 6th and the 5th strings are used to keep a moving bass line flowing. For example, a G major chord can be played a G on the bottom at the 3rd fret of the 6th string and then played at with the B on the bottom at the 7th fret. There are numerous jazz guitar books available that will teach you the basics. Once you have mastered four string jazz chords and apply them to the 6 string banjo you can easily make your six string banjo sound like a tenor banjo.
Develop a repertoire of old jazz standards.
Tune the banjo to open G. Open G is the standard tuning for the 5 string banjo. It is also a popular tuning for acoustic blues guitar. Starting with the low string the tuning is D G D G B D. This tuning allows you to play chords by simply laying your index finger across the fret. Lay your finger across the 5th fret. This is a C major chord. Play a D major chord by laying your index finger across the fret. Play a G major chord by strumming the open strings or laying your index finger across the 12 the fret.
Learn to play with thumb and fingers. 5 string banjo players and acoustic blues guitarists play with their thumb and fingers rather than a guitar pick. Bluegrass banjo players use thumbpick and fingerpicks. Some blues guitarists use thumbpicks and others use the bare thumb. Practice playing arpeggios. An arpeggios is a chord in which notes are played successively rather than altogether. Play a G arpeggio by playing 5th string with your thumb and the G B D strings with your index, middle, and ring fingers.
Practice synchronising the thumb and fingers. Since the banjo is tuned to open G it is possible to play a melody with your fingers while your thumb plays a G chord. This is what produces the full and thick sound of the bluegrass banjo and of blues guitar as well. Start picking out melodies on the first three strings with your fingers while using your thumb to play the three lower strings.
Incorporate banjo rolls into your playing. Banjo rolls are an essential part of bluegrass banjo technique and they are what allow the banjo players to play at lightning speeds. Country guitar players often use this technique in their bag of tricks as well. A banjo roll uses the thumb and the index and middle fingers. Play the 3rd string with your thumb, the 2nd string with the index finger, and the 1st string with the middle finger. Begin by playing triplets, three notes per beat. Gradually increase the speed. The goal is to play as fast as possible. Use the same pattern on all six strings. Play the 6th, 5th, and 4th strings: 5th, 4th, and 3rd strings, 4th, 3rd, and 2nd strings, and the 3rd, 2nd, and 1st strings.