It took me a long time to learn about private messages. Once I found this forum I find it very useful when I want to respond to someone in a critical manner. Better this than on a public post. If you just want to make the person look bad then a public post is the way to go. If you want to give them information go the PM route.
Today I just learned (thanks to Pam and Dave) that even after a PM is read it takes up room in my mail box. So, now I know to delete regularly.
Any other suggestions?