Get a box on the other side of town, separating yourself geographically from your mail. Avoid those franchise mail centers that you'll find in malls and strip centers. They're all so afraid of upsetting the apple cart that they require more identification than the regular post office. They'll roll over quicker than a friendly dog, providing any junior G-man with a tin shield access to their records and your mail. Utility companies, banks and such provide a place on their monthly mailings to enter a change of address.
Magazines often have a small form or an address to mail a change to as well.
The post office computerizes COA records, renting the lists to various businesses and organizations. When first setting up phone service, provide a fictitious name, or that of a dead relative. You may have to put up a small deposit, but once you've established credit with your local Ma Bell, you can get a phone under your assumed name anv where in the country. This tactic enables you to escape the various databases that collect and collate information based on phone numbers. It won't eliminate those pesky sales calls - only getting rid of your phone will do that.