2. Buy a notebook. They sell ones that have a calendar in the front and an address book in the back.
3. Use a stamp and an envelope. The USPO does not keep a record of all sent or received packages. Public drop boxes are also widely available, PO boxes which mask your identity from the sender, and third party mailboxes to mask your identity from The Man. I mean, really, if you're going to send messages to your mistress, girlfriend, lover, or wife, at least have the class to send paper letters she can keep in a lockbox for her great-grandchildren to find after she's dead.