When creating thematic maps with CartoDB's Data Observatory, it's essential to consider several key factors. First, choose an appropriate map type based on whether your variable represents categories or numbers, and select from various thematic map types such as choropleth, proportional symbol, or dot density maps. Next, determine the right classification method for your data, aiming for 3-7 classes to avoid overwhelming your map reader. Select a color palette that maintains uniform saturation and lightness levels, using discrete colors for categories or sequential/diverging palettes for numbers. Additionally, consider creating a simple basemap to provide context, and choose a projection that preserves area, especially when summarizing information about areas. By applying these cartographic tips, you can create visually appealing and informative thematic maps that effectively communicate your data insights.