So, you’ve heard that Apple is announcing a new iPhone very soon. Now what? It’s time to sell your current iPhone, of course!

There are many ways to resale your used iPhone 4 to make some extra cash, and we’ll show you everything you need to know to get your iPhone ready for its new owner…

Step 1: Backup and Restore

Before you do anything, you want to plug your iPhone into iTunes and backup your data. Once you’ve synced with iTunes, you want to restore iOS to the latest version. This can be done on your iPhone’s device Summary page. If you’re jailbroken, you’ll need to restore in iTunes to un-jailbreak your iPhone.

Restoring your iPhone to its factory settings will remove your personal data. You can also wipe your device clean in the Settings app. Navigate to General > Reset. Tap Reset and then “Erase All Content and Settings.” Depending on your device, this could take awhile, as iOS must literally wipe itself byte by byte. Make sure you’ve got a full charge or plug into a power source.

When you’ve restored to the latest version of iOS and removed your personal data, you’re ready to proceed.

Step 2: Take Care of Your SIM Card

You never want to sell your iPhone with your SIM card. The SIM card is yours, and it’s associated with your phone number and carrier information.

The AT&T iPhone 4 has a MicroSIM that is super easy to remove. Older iPhones don’t use a MicroSIM, so be aware of that. On an AT&T iPhone, just pop the SIM out (if you don’t know how to take your SIM out, refer to this tutorial). You can pop the MicroSIM into your next iPhone, and AT&T will even take care of that in the store for you.

On a Verizon iPhone, things get more tricky. Because you don’t technically have a SIM to remove, you need to either activate a new phone on your account or call Verizon and ask the carrier to deactivate the iPhone for you. If you’re selling your current iPhone in anticipation of the next generation model, then activating a new phone is not really an option. However, if you have a cheap CDMA phone lying around, you could temporarily activate it on your Verizon account while you wait for the next iPhone.

Step 3: Clean Your iPhone

Now that you’ve cleaned up your iPhone software-wise, it’s important to make sure that your iPhone is also spotless on the outside. If your iPhone has a few dings and scratches, don’t fret. You probably won’t get as high of a resale value, but many resellers and buyers don’t care about a few minor scratches. Just make sure to be honest when describing the condition of your iPhone.

Apple has a great support article about how to properly clean its products. For the iPhone, use a soft, slightly damp, lint-free cloth to clean dirt and grime off the device’s surface. It’s best to turn your iPhone off before you clean, just in case you get too much moisture in an opening.

Apple says to not use window cleaners, household cleaners, aerosol sprays, solvents, alcohol, ammonia, or abrasives to clean an iPhone. It’s recommended to just use a dry cleaning cloth. Mobile Cloth offers some very good, affordable cleaning cloths for gadgets like the iPhone. If you want to use some sort of cleaner, make sure to not directly apply the liquid to the device.

Step 3: Get Your Packaging Together

You did keep your iPhone’s original packaging, didn’t you? Assuming that you did, find and collect the packaging to sell alongside your iPhone. Buyers like it when a used iPhone comes in the original packaging because it says that the previous owner took care of the device.

If you’re posting your iPhone on a site like Craigslist or eBay, then presentation is important. Assemble your iPhone next to its original packaging and take a nice set of pictures to post online. You should include the charger, manuals, etc. If you used the Apple earbuds, then don’t bother including those. People don’t usually want used earbuds.

If you don’t have your iPhone’s original packaging, then head over to your local US Post Office. There will be some fairly inexpensive packaging options available. If that doesn’t cut it, then places like UPS have a spray-in material that will mold itself to the shape of your item.

Jailbreaking and Unlocking

If you want to unlock your iPhone before you resale, then see our unlock page to learn more. Unlocked iPhones can typically sell for $100 more on sites like Craigslist. Selling a jailbroken iPhone 4 could also result in a higher resale value. If you’ve got an untethered jailbreak on iOS 4.3.3, then you may want to consider keeping that jailbreak as added value. Things can get hairy when you’re trying to sell a jailbroken, unlocked iPhone on the used market, so consider that as an option if you’re comfortable with what you’re doing.

Stay tuned for a follow-up on the best places to resell your used iPhone!