• Put a copyright symbol on the first page. You may think your prose needs some protection, but a) it's probably not so good that an agent or editor is going to risk her entire career to steal it and b) you just look unprofessional. A lot of people seem to believe that you have to register to obtain copyright protection or at least include the little copyright symbol. However, you do not need to do EITHER of those things. Your work enjoys copyright protection from the moment it is created. When you get published, your publisher will take care of registering the copyright.
• Put a copyright symbol on every single page just to be extra sure.
• Put "North American Rights" on the cover sheet. Your agent will negotiate rights with your publisher. You currently own all the rights. If your editor makes your agent a big enough offer, they will purchase world-wide rights.
• Speak for the book. If you label it "An Amateur Sleuth Turn-of-the Century Hawaiian Murder Mystery" it just feels like you are leading me by the hand too much. Just put down the name of your book on the cover sheet.
(Full disclosure and caveat: I'm not an agent. These are just my opinions.)