Several things to check on an overheating vehicle, when the engine is at operating temp, feel the top middle and bottom of the radiator(front of rad, opposite side of fan!) if there is a cool spot , you have a blockage. Feel the inlet and outlet heater hoses,if they are cool, again blockage in heater core.
Do a pressure test of the cooling system.(you can rent a press tester at most auto parts stores, press test will show external leaks (hoses, water pump, radiator etc). Just a few easy things to ck, good luck