This tip applies only to US Residents.
US Residents are very familiar with the clutter in their mailbox from credit card companies, insurance agencies, retailers and other service providers with "pre-approved" offers of credit and what not. You can opt-out from receiving these unsolicited mails by filling in an electronic opt-out form at this website - https://www.optoutprescreen.com/. You have choices to opt out for 5 years or permanently for life. The website also provides an option to opt-in in case you want to get those offers again.
This has a two-fold use:
1. You are reducing paper waste
2. You are minimizing the chances of identity theft. Think of all the pre-approved offers ending in the garbage/recycle can only for somebody else to find out your personal information on them.