Whether you're writing a commercial you hope to get picked up for a contest or filming for a major retailer, you need skills for directing child actors. Keep your script suitable for the age you're working with. Also, when planning the shoot day, make sure to give them special schedules. These are often referred to as "call times" in the industry. Usually, a parent or guardian will be responsible for the child's "call time".
Use simple words in your script so the child actors don't get confused by the language. If you hold auditions first, you can see how they react to the words and rewrite the script before shooting if necessary. Although you can help them sound out the words, you don't want the kids focused only on the language. You're typically hiring child actors for their expressive faces and body language. If they start thinking too much about the words, less emotion might come through from their faces. Simple words are also less intimidating for children.
Storyboard the script to keep the child actors working short shooting days. They tire easily and might become frustrated as the day goes on and they stop being on top of their game. Luckily, a commercial is typically a short shoot day. If your child actor is the main star, be sure to give him plenty of breaks to study, eat and drink. He must be well rested to avoid a melt down or temper tantrum. Even if he is non-union and you do not have to follow regulations of the Screen Actors Guild, following guidelines for him to have several breaks is necessary to keep the shoot running smoothly.
Watch the language of other actors on the shoot days that the child actor is there. According to Children in Film's article "Responsible Producing," everyone on set should give positive feedback to child actors. They're typically sensitive to advice and praise from more seasoned actors and filmmakers, which means that crew and cast should treat them with respect.
Writing a commercial script for a kid can be simple–avoid overcomplicating your idea. For example, a company selling peanut butter might reach higher sales with a straight forward concept. A kid smacks his lips and says, "Mmm!" A voiceover speaks in the background about how all the moms appreciate the peanut butter brand that their kids love. That kind of script markets the idea to the moms and the kids, which might appeal to a wider demographic. The key to selling the product is to get the right kid–he should have charisma and charm. His personality may be more important than his ability to read a script well. Commercial shoots work well when kids improvise away from the script and let their personalities shine.