How to use Protractor effectively for measuring angles accurately?

To use a protractor effectively for measuring angles accurately, place the center of the protractor on the vertex of the angle. Align one side of the angle with the 0-degree mark on the protractor. Read the measurement where the other side of the angle intersects the protractor. Make sure to use the correct scale (either 180 degrees or 360 degrees) based on the type of angle you are measuring.