What is the sources of error and suggestion on how to overcome it in the hooke's law experiment?

In physics, Hooke's law is written in equation as:

F = kx

It states that the force F exerted on the spring is directly proportional to the displacement x by a constant called spring constant k.

In the laboratory, this is done in an experiment through the apparatus shown in the attached figure. The object experimented here is the spring, and you are to find the spring constant. A known mass of object is attached below the spring. That object carries a force in the form of gravitational pull in terms of weight. When the spring stretches, the displacement is measured with the use of the ruler.

There are a number of sources of error for this experiment. First, the reading from the ruler by the reader may be inaccurate. That's why digital balances are much more reliable because it minimizes human error. Reading the measurement on the ruler is subjective especially when you don't read it on eye level. Second, the force of the object might also be inaccurate if you use an unreliable weighing scale. Lastly, the apparatus might not be properly calibrated.