Right Arm Position
Here is a little tip that will help you to find a consistently good right hand and arm position on the banjo head. If you look at the photos notice how my lower arm from the elbow down to my wrist is on a parallel plane to the head and neck of the instrument. It never falls behind the banjo or gets tucked in by my side. You will also be able to get slightly more pressure on the wrist by using this set up because the wrist needs to be anchored some way on the banjo skin or head. It is the wrist that revolves around a point of contact on the banjo head and not the arm, this is important.
I always take off the arm rest that most banjos come with as it suspends my wrist too high and I can't get any firm contact or pressure for my wrist to move around.
You might suggest that the sound of the banjo is muted with this technique. This may be true but most banjos used for Irish music are arch top tonerings and not flathead like the bluegrass banjos. They already sound bright and have a more piercing sound quality. This technique or playing position will feel like you are sticking out your elbow to give someone a dig in the ribs, but trust me, it works and I bet most players haven't even noticed that I do it naturally.
I have included some photos of the wrist positions that I have seen over the years with players encountering problems with Irish music. The most common position is where the wrist is placed below the strings and when that happens the strings have to be plucked with an upward movement of the wrist which can be very painful after a while and also doesn't get the best tone from the banjo because the strings are not being hit in a powerful downward motion. Music is full of rhythm especially Irish traditional music so the natural movement to tap out time is with a downward stroke even when one taps out a beat with a pen on a tabletop. Bring this aspect to your banjo playing.
Keep your wrist slightly above and behind the bridge and start every tune with a down stroke just like a guitarist or a violinist. Also try and hold the plectrum with just the thumb and index finger taking care not to let your thumb collapse inward this is important. This is a lot easier and once you get used to it, you never have to keep looking for that magical grip or hold that you think will improve your playing. Get these correct and you can concentrate on the music.