The guide on visualizing time-series data emphasizes best practices in selecting and structuring charts to effectively communicate insights over time, without delving into the technical aspects of chart creation. It highlights the importance of choosing the right type of visualization, such as line, bar, area, trend, and waterfall charts, each suited for different purposes like tracking trends, comparing values, or illustrating cumulative totals. The article stresses the need to focus on a single message per chart and structure data accordingly to match visualization goals. It advises using Metabase's Offset function for efficient comparison of metrics over time and cautions against making misleading conclusions from stacked area charts. The guide encourages hands-on practice with Metabase to create impactful time-series visualizations and provides additional resources for further learning.