Harmonies

Here's a post I made on the Home Recording BBS:

I've been looking around for information on writing vocal harmonies but haven't been able to find anything decent. Anyone I ask seems to say "you just do them" but that seems scary and wrong to me. Can anyone share any tips or guidelines or anything?

Do you just work them out methodically based on the key or do you feel your way towards them and practice eventually makes it intuitive? It seems to be hit and miss with me. Sometimes I can come up with a harmony line and other times I'm just lost.

Some interesting replies.