What are some techniques for creating dynamic speed lines in Illustrator to enhance action scenes?

Use the 'Blend Tool' to create smooth transitions between lines of varying thickness and color. Alternatively, the 'Width Tool' can manipulate line stroke profiles for tapered effects. Experiment with different stroke caps and corner types (round, bevel) to achieve the desired look. You can also draw individual lines and then use the Rotate tool or the Free Transform tool for added dynamism.