Question: what should i do before giving my iphone away?
Answer: Unpair Apple Watch. If you paired an Apple Watch with your iPhone, unpair your Apple Watch.
Back up your iPhone. ... 
Sign out of iCloud and the iTunes & App Store. ... 
Turn off Find My iPhone. ... 
Deregister iMessage on your iPhone. ... 
Erase all your iPhone's Data and Settings. ... 
Remove iPhone From Your Apple ID Account. ... 
Remove SIM.