The fine writer Dan Baum, formerly of the New Yorker and the author of Nine Lives, has a blog that’s required reading for freelancers. He talks shop with advice on everything from paying the bills to making people speak:
Here’s the little secret they taught me at The Wall Street Journal: Whenever someone offers to tell you something “off the record,” they really want to tell you. So if you decline their conditions -- can’t attribute it, can’t use it -- they’re going to end up telling you anyway. They can’t resist. So it’s best to refuse the conditions and just be patient for a few minutes.
After reading a few posts, I already feel like a better writer.