I talked a local historical organization into once-a-year dues mailing and
paying.  The result was that they reported 90% paid and all at once, more
funds at one time from one mailing than ever before.  There's a trick of
enclosing an addressed envelope (no postage) so the person doesn't have to
hunt an envelope.
 
I do recommend that if you've had a policy that each member was good for
one year from the time they joined, you need to (1) announce the intention
to create a new membership year (say, September to September)...and (2)
grandfather in all those who joined in say, the last six months
 
Dean DeBolt, University of West Florida
and Board member, Pensacola Historic Preservation Society