a supplemental publication from the WES in 2013, by Jeremy Collingridge. Similar in advice to the links provided by Jim Chisolm.
If you have a substantial collection of value you have to think about it's ultimate fate sooner rather than later.
This publication is available to members and covers the essentials:
Preparations : Knowing what you have
How to determine values.
Donate to museum or auctions, methods of sales by your survivors.
...and much more. Plan ahead, it's the kinder thing to do for your family.