101 : choose the right chart type for your data
Data collection associated to a relevant representation will help you to:
> Separate what you think is happening from what is really happening by seeing the history over time, measuring the impact of changes on a process or just monitoring process performance.
> Analyze cause / effect relationship and therefore avoid "solutions" that do not solve the real problem.
> Establish a baseline of performance.
As pictures speak louder than words ; hereunder a simple flow chart taken shamelessly from the Internet. I would just add one thing on top of it: use a whisker plot to compare a group of variable date over time either on many or few periods.
If you have any question or if you want to share some hints & tips, feel free!