How do you use sensory details and imagery to enhance your descriptions for children?

One thing to remember about children is that they generally don't develop the capacity for abstract thought until around twelve. As such, more colorful parts of speech like similes and metaphors need to be used very intentionally and may need to be spelled out for them. Not literally but to make it a little easier to understand. - "It was the kind of cold that seeps into your bones" vs "It was so cold that no matter what you did you couldn't seem to get any warmer." - "The old dog smelled like death." vs. "The old dog smelled so bad it made your eyes water."

If writing anything with pictures (a book for young children), the writing can tell the story and be enhanced by pictures. The images should likewise enhance the writing. Don't depend on your pictures to show you what's missing in the text. They need to complement each other. How are your characters feeling about what's happening in the story? When they are nervous do they fidget, when they're happy do they bounce up and down, etc? Show with words, complement with pictures. Finally, read your text aloud. Do you know what's going on without images? Are you following along & interested? If not, edit your text.

An important skill when it comes to writing descriptions is to know when to STOP describing! Let your reader fill in the details. Take this description of a castle, for instance: "As I turned the corner, I saw the dark castle looming atop the hill. Lightning struck the sky, illuminating the looming towers of marble. The windows showed no light within, save for the room at the tip of the tallest tower." I didn't say how big the castle was, how many towers it had, or whether or not there was a drawbridge leading across a moat. Let the reader create the story in their own mind.

Depending on the age of your audience less detail allows them the opportunity to create their own. This type of thinking, skill is critical to assist them in moving away from purely concrete thinking ...

When you read your piece aloud, especially a piece written for children, do the voices for your characters! Not every character is going to sound the same, or even sound like you. Some might be more formal, while others might always use improper grammar. Creating consistency in the way that your characters speak and sound is crucial for getting them into the minds of your readers.