It's not always best to learn estate planning from celebrities. However, their high visibility failures can be instructive. Consider the recent passing of Adam Yauch, of Beastie Boys fame.
Forbes recently analyzed the Last Will of Mr. Yauch in an article titled "Part Of Beastie Boy Adam Yauch's Will, Banning Use Of Music In Ads, May Not Be Valid." It seems one of his last decisions and last acts of defiance, was to make pen-and-ink revisions within a common legal provision. Unfortunately for Mr. Yauch, the language he chose and the addition itself did not work.
So, what went wrong?
The Last Will already specified that Mr. Yauch's image and name aren't to be used for any advertising purposes, but then he penciled in "or any music or any artistic property created by me." Unfortunately, since the music of the Beastie Boys doesn’t belong to Yauch in the same way his image does, it also belongs to the other Beastie Boys. Bottom line: Mr. Yauch injected a provision related to copyrights into a statement about publicity rights.
For a complete analysis of that mistake, the original article is an interesting read. In the end, while you may be able to stain your deck without jeopardizing your estate, making DIY pen-and-ink changes should be left to professionals.
Reference: Forbes (August 13, 2012) "Part Of Beastie Boy Adam Yauch's Will, Banning Use Of Music In Ads, May Not Be Valid"