How can accuracy of a measurement be improved?
The chief way to improve the accuracy of a measurement is to control all other variables as much as possible.
Accuracy is a measure of how close your values are to the true value. Precision is a measure of how closely your successive measurements agree with each other.
It would not make sense to use a measuring device capable of four decimal places if your successive measurements do not agree to one decimal point.
Use the best device available, but keep everything else as constant as you possibly can.