Ask HN: I'm going to have to lay people off, and want your advice

Throwaway for obvious reasons. I'm probably going to have to lay off several dozen people, which I've never done before. Needless to say I'm not looking forward to it. What advice do you have to make it as decent as possible both for those who will be laid off and those who will remain?

(Probably helpful if you note whether you are someone who has been laid off well or poorly, someone who has laid people off, or just have thoughts about it.)