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 have moved on in the cycle of analytics. 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 in how well the data story is told.

Here are some of the things you should consider:

• Audience: Who is the audience and what are the needs of the audience?
• Goal: Is the goal to evoke an emotional response or to lay out the facts for an impassioned decision? Are you highlighting an action that needs to be taken, or simply trying to generate interest in a topic?
• Setting: This is the environment in which the data story is communicated. Is it a formal business meeting where the format should reflect a high level of professionalism? Is it going to be shared on a blog informally?
• Mode: How will the visualizations be presented? You'll want to make sure rows, columns, fonts, and marks are large enough for a projector or compact enough for an iPad. If you are publishing to Tableau Server, Tableau Online, or Tableau Public, then did you select fonts that are safe for the web? Will you need to use the device designer to create different versions of a dashboard?
• Mood: Certain colors, fonts, and layouts can be used to set a mood. Does the data tell a story that should invoke a certain response from your audience? Is the data story somber or playful? The color red, for example, may connote danger, negative results, or indicate that an action is required. However, you'll need to be sensitive to your audience and the specific context. Colors have different meanings in different cultures and in different contexts. In some cultures, red might indicate joy or happiness. Also, red might not be a good choice to communicate negativity if it is the color of the corporate logo.
• Consistency: Generally, use the same fonts, colors, shapes, line thickness, and row-banding throughout all visualizations. This is especially true when they will be seen together in a dashboard or even used in the same workbook. You may also consider how to remain consistent throughout the organization without being too rigid.

All of these considerations will inform your design and formatting decisions. As with everything else you do with Tableau, think of design as an iterative process. Seek feedback from your intended audience often and adjust your practices as necessary to make sure your communication is as clear and effective as possible. The entire goal of formatting is to more effectively communicate the data.