How to write a great technically correct direct response letter.
Somebody (on Twitter I think) recently recommended Winning Direct Response Advertising by Joan Throckmorton. I bought a copy and can tell you that it is amazing. I strongly recommend getting your own if you can hunt one down.
It features a fabulous example of the use of effective technique required for writing a brilliant four page DM letter that just happens to contain loads of useful insights for fundraisers. I've taken a few pics and added them below. And don't forget, loads of these ideas work for email comms too.