Answer to Question 1
One way to do this is to increase the number of calibrated subdivisions (the least
count) that are marked on the measuring instrument or you might choose a better type
of measuring instrument all together. Example: Use a vernier caliper instead of a
meter stick.
Answer to Question 2
Take more readings to make the average better and take more care in using the
measuring instruments to provide as many significant digits as possible in your data.