Selling your old phone
How to prepare a phone for sale: backup and data transfer, two-factor, unlinking accounts, resetting in the right order, honest photos and a safe handover.

[ ] Make a backup and verify it
    Check that the backup exists and opens, not merely that the setting is on. After the reset it is too late to check.
[ ] Move your data to the new phone and check it
    Photos, contacts, chats, notes, passwords. Use the new phone for a few days before selling the old one.
[ ] Move two-factor authentication
    Authenticator apps and confirmation codes. This is the step that costs people access to their accounts after a sale.
[ ] Unlink payment methods and transit cards
    Cards in the wallet, device-linked subscriptions, passes. Do it before the reset, not after.
[ ] Sign out of every account
    Email, cloud, messengers, banking, social media, streaming. In the browser too, not only in apps.
[ ] Unlink the phone from the manufacturer account
    This step is mandatory: otherwise the device stays locked to you and the buyer cannot use it.
[ ] Remove the SIM and memory card
    These are forgotten inside more often than anything else. Check the tray even if you are sure.
[ ] Test cameras, sound, buttons and charging
    Both cameras, speakers, microphone, vibration, sensors, Wi-Fi and the port. The buyer will test this — better to know first.
[ ] Check the battery health
    It is the buyer's first question. An honest figure saves both sides time and reduces haggling.
[ ] Clean the body, port and speakers
    Carefully, with no liquid in the openings. A clean phone looks better and sells faster.
[ ] Gather the box, cable and paperwork
    Completeness noticeably affects the price. A receipt and warranty card, if you kept them, help too.
[ ] Photograph the phone honestly, in daylight
    From every side, including chips and scratches. Honest photos filter out people who arrive to argue about condition.
[ ] Perform a full reset once everything else is done
    Only in this order. A reset before unlinking leaves the phone locked to you.
[ ] Check real prices for the same model
    Compare listings with the same condition and storage, not the price of a new one. You avoid underselling and month-long waits.
[ ] Arrange a safe meeting
    A busy place in daylight. Let them test it, but do not leave your SIM inside and do not follow anyone into a stairwell.
[ ] Wait for the money to actually arrive
    A screenshot of a transfer means nothing. Never read out a code from an SMS — that is always a scam, whatever the story.
[ ] Remove the device from your accounts after the sale
    Revoke sessions, check the device list in your email and cloud, confirm codes arrive on the new phone.

Checklist from Unload: https://unloads.me/c/sell-phone