Margo thinks twice / written and illustrated by Monica Arnaldo.

Enhanced descriptions from Syndetics:

Margo is an imaginative, adventurous little girl who has just one problem -- worry has found its way into her life. She sometimes feels nervous and uncomfortable, especially inside the wild world her imagination sometimes creates. Whenever her mom gives instructions, Margo's mind turns the everyday advice into worries and worst-case scenarios. Mom tells Margo to be careful with the craft glue, and Margo imagines becoming stuck to all the furniture and decorations in her room. Mom advises Margo not to swing too high, and Margo envisions ending up on the roof.

Monica Arnaldo's warm and inviting mixed-media artwork brings these flights of fancy to life, playing out Margo's fears and highlighting her expressive face. Luckily, Margo's mom comes up with an idea to ease her daughter's anxieties and encourage her inventive spirit in a positive way. Careful readers will pick up on subtle hints throughout the book before the secret is revealed: Margo's family adopts a pet dog! He's energetic, friendly, clumsy, and messy--just the outlet she needs to snap out of her worries.