Safety first: Send your essential data to the Cloud or a hard drive. That means your contacts, photos, music, apps and anything else you wouldn't want to lose. Backing up your phone will allow you to restore it on your new device, setting up just like the old one in no time.
Wipe It Clean
Remember: Putting your sensitive data in the trash doesn't mean it's gone! You'll need to do a clean system reinstall (on a computer) or "restore factory settings" (on a smartphone or tablet) to make sure all your data has really been removed.
Deauthorize Subscription Services
Your account with services like iTunes, Netflix, the Xbox store or the Wii store has personal information and is linked to your device. Before you sell it, make sure you deauthorize that device or unlink it from these services so the new owner can't rent movies or buy games on your tab.
Wipe It Clean (on the Outside!)
Plain and simple: The better your tech looks, the more money you're likely to get for it. (Learn more about the right way to clean your tech here.)
Quit "Finding" Your Phone
For Apple mobile devices or computers, make sure your phone is no longer "findable" by Apple's "Find My Phone" feature (which you can turn off in Settings > iCloud on a phone, or in System Preferences > iCloud on your computer).
Remove SIM cards, SD cards, DVDs and games. Sure, seems like an obvious enough step, until you realize a week after selling your old Xbox that your favorite game went along for the ride, free of charge. Open up every port, latch, cover, slot and drawer on the electronic you’re selling and hang on to all your media.
Take Great Pictures
Buyers are likelier to take the plunge if they can clearly see all the details, dings and all. Don't try to hide imperfection: Being honest means you won't end up with a dispute on your hands.
Plan Ahead for Future Sales
To ensure you'll earn top dollar next time around, skip the engraving or personalization, use a case and a screen protector, and hang onto the box and accessories.