Visualization considerations
Tableau employs good practices for formatting and visualization from the time you start dropping fields on shelves. You'll find that the discrete palettes use colors that are easy to distinguish, the fonts are pleasant, the grid lines are faint where appropriate, and numbers and dates follow the default format settings defined in the metadata.
The default formatting is more than adequate for discovery and analysis. If your focus is analysis, you may not want to spend too much time fine-tuning the formatting until you are getting ready to share results. However, when you contemplate how you will communicate the data to others, you might consider how adjustments to the formatting can make a major difference to how well the data story is told.
Sometimes, you will have certain formatting preferences in mind or a set of corporate guidelines that dictate font and color selections. In these cases, you might set formatting options in a...