Pixlr Editor is a free image editor that runs in a web browser and may serve as an alternative to Adobe Photoshop. The Pixlr Blog contains basic tutorials on simple image editing, including how to use the lasso tool, create layers, and adjust colors.
These video tutorials teach the basics of creating vector art in Adobe Illustrator. While the tutorials are free, Adobe Illustrator requires a subscription.
This section of Duke University’s Data Visualization LibGuide compiles useful resources for choosing appropriate visualizations for data sets, including a data visualization catalogue.
Though framed from an economist standpoint, this Journal of Economic Perspectives article by Jonathan A. Schwabish provides a good overview of data visualization and different presentation strategies.
This free three-part WebJunction webinar series discusses the current state of public library data, various sampling methods, and meaningful measures for the future.