You have see the phone which you want to buy and which is second hand some steps of tips below:
1. you have check the phone properly which has not body damage.
2. After check the phone you have use this phone for 1 or 2 days for checking its performance.
3. You have see this phones ecessserios which is at good condition or bad.
4. Your phone is legal or not means it not from fruad sellers.
5. You have take look at mobile phones price and seller tell you what price. If he or she tell more than half price than say no them.
This are the tips you should know to buy second had phone.