Goofus, Gallant and You
Ask the right questions, and then measure the results. And if you have to, change back. It's far better to have tried it and concluded the old way was better than to continually miss out on significant improvements because you were afraid to try.
Know when to stop talking - and when to listen
Gallant would remind us that sometimes it isbest to listen and learn - and that's true with donors, too. There's a time to stop mailing, e-mailing, calling, etc. Sometimes a donor stops giving - and nothing you do can change that. Continuing to "talk" at them is just white noise in their lives.