Identify a Boeing 777

Steps

The plane's model number will be generally written below the cockpit window on both sides.
Look at the wing and see if it has 2 engines (One on Each Wing).
Check for winglets. If it has any sort of winglet, it is not a Boeing 777.
Look at the end of the wings. At the end of the wing, does it have a flat end with a backwards nozzle coming out the back?
Look at the side of the plane. Does it have 4 or 5 full size (non-emergency exit) airplane doors on each side?
Determine how tall it is. Is the plane only one floor tall? Check that there is only one row of windows throughout the entire plane.
Look at the length. The Boeing 777 is noticeably long. You should be able to tell that it is longer than almost all of the other planes.
Consider the engines. The engines are quite large. See if you can spot the engines and check if they look bigger than most other plane's engines.Also, the 777 has the exhaust cone visible which distinguishes it from the Airbus a330-300.
If you see it in the landing phase check the landing gear of the plane.Each set of the gear should have three pairs of wheels which differentiate it from the Airbus 330