Designing a structure for a personal database

I have decided to rewrite a couple of applications that use my
personal information database and I'm looking for ideas on how to
structure a new database for them.

For most purposes I want to communicate with a family or business at
its "home" address. For example, "Fred and Betty Bloggs" or "Acme
Widgets" have a specified street address and telephone number. It is
possible that the Bloggs family has a holiday house or I have to deal
with Acme Widgets at more than one location. I also need information
about individuals such as mobile phone numbers and birthdays but I
don't want to duplicate shared home and business addresses and
telephone numbers. For example, Betty Bloggs could work for Acme
Widgets and share a town house and a country house with Fred.

Please ignore any database structure implied in the preceding
paragraph. I'm looking for the ideal PIM database structure and you
probably understand the requirements better than I do. No doubt you
have been frustrated by the address books in many applications that
insist you supply all the details for every individual.

My excuse for posting in comp.lang.java.databases is that I follow it
and the applications will be written in Java and use Derby as the
database. I confess that the reason is to canvas a wider audience but
I refuse to admit the post is spam.