We all have that problem and the problem behind the problem is that we do not know what the other person likes to see in an email or letter or her or his interest in the family tree.  I suspect most people already know how interested they are in helping as soon as they read your note.  It simply will not persuade them.  For those who cooperate, you do not know how much information they want to see or can even understand.  That is why my messages have a two pronged approach.  Three or four sentences about why I am writing, the potential relationship, and asking for their help.  And then I include the data which have the matching names.  This is two create a record of why I am contacting the person and to establish my creditability and legitimacy.   

Even with all this, I get about one out of ten to respond and very, very few relatives who traditional genealogy can confirm.

Good luck and keep writing those letters.
--
Bob Silverstein
bobsilverstein@...
Elk Grove Village, IL

Researching Kaplan (Krynki, Poland) Tzipershteyn (Logishin, Pinsk, Belarus), Friedson/Fridzon (Motol, Cuba, Massachusetts), Israel and Goodman (Mishnitz, Warsaw, Manchester).