If you want to get a accuracy reading, a high quality Bimetal thermometer is necessary , and also should use the right way of the measurement , they are :
First observe the measurement range,grading value and 0 points, the measured liquid temperature can not exceed the measurement range
The sensor part of stem of the thermometer is completely immersed in the liquid under test. Do not touch the bottom or wall of the container.
The thermometer should be immersed in the measured liquid for a moment, and then read after the thermometer's indication is stable.
When reading, the stem of the thermometer should remain in the liquid, and the line of sight should be equal to the dial scale which the pointer points.
The good quality thermometer and the correct methods are the ways you can have a accuracy temperature.