Before selling any old computer or laptop, you need to protect your privacy first. Step one: back up your important files, following the "3-2-1" rule (three copies, on two different types of storage, with one kept offsite) via an external drive or cloud storage. Next, do a full factory reset on the device so it's completely wiped of your personal data. Finally, don't forget to protect your new device too — with a VPN, antivirus software, and a password manager, since new devices ship with zero protection out of the box.