1.  Be sure to spell the agent's/editor's name correctly and have the proper address.

2.  If you've met the agent/editor at a conference, mention it.

3.  Tell if you've been referred by someone. 

4.  GET TO THE POINT.  Tell what kind of book it is, work length, and if it's finished.

5.  Watch the tone.  There's no need to be cute or overly dramatic; a straight business letter will suffice.

6.  Give no personal information unless it has some bearing on the book.

7.  Misspelled words are the kiss of death.

8.  PROOFREAD.

9.  Practice writing a blurb.  If you're satisfied with it, use it as your first paragraph as a quick sales pitch.

10. Enclose a return envelope and postage, or say that you don't want the manuscript returned.  DON'T use metered postage on a return envelope.

11. If you want to know if the agent/editor received the material, include a stamped postcard.

What to put on postcard for notification that your manuscript has been received by the editor/agent/publisher.

Note:  Place Y0UR name and address in the address slot!