M. Ted I would also be VERY interested in hearing such advice. My new a cappella group consists of four people and so far the harmony we do is stuff we improvise while rehearsing and try to remeber what sounded good and keep it! We have no "artistic director" to decide on final arrangements. I have done some arranging and have tried to help with this but since I grew up singing soprano (and often take the melody line with this group since I have a bigger and higher voice than the other two women) hearing harmonies is tricky for me and does not come all that naturally. I find it a tad frustrating since I come from a choral background and read music; the other members are not comfortable with this approach. And yet to be a successful a cappella group we WILL need to find a way to work in harmonies a bit more effectively.
so suggestions from experts like Animaterra would be welcome!!!