I've started teaching myself how to play the English concertina from tutorial books and online videos. The hardest part of the instrument seems to be not learning the keyboards or even how to work the bellows, but building up hand strength.
While playing, the weight of the concertina is supported by one's thumbs and pinky fingers. (Even when supporting the instrument with one's knee or a strap, this is still at least partially the case.) My pinky fingers are finding this particularly difficult. Playing on my knee or using a strap makes it harder to actually play, although this may simply be a matter of getting used to these positions.
Question: How can I hold the concertina so that it will place less strain on my fingers and hands, yet allow me to play easily?
Edit: I'm having particular problems with my right thumb, and want to make sure to avoid stress on my thumbs.
Edit 2: Dave's answer was good, and I ended up using a neck strap and sometimes supporting the instrument with a knee (or a table).
I've since sold the instrument, but if I ever return to the concertina I'll place more emphasis on getting a lighter instrument that's easier to hold and manipulate. (I'm fairly sure a heavier student-grade instrument like the model I had is harder to play and hold.) I'd also spend more time doing warmup exercises with my hands, as I do when playing guitar.