Whenever you buy a mobile phone then Just remember that Battery should be very good.
RAM should be equal to or more than 2 GB.
Camera should be 8 MP back and 4 MP front.
Processor should be Quad core or More.
If android version then Updated and latest version installed.
Always click photo on shop to check clarity of mobile camera.
Always check sound or audio by playing on that time.
Always take care about latest and good products in the market.