How much product should I use per wash, and can I use it daily?

The instructions say "a small amount" — for most children with short to medium hair, that's roughly a 10-cent coin sized dollop (about 5–7 ml). Start with less; you can always add more if the foam doesn't spread easily. The mild surfactants produce a soft foam rather than a dense lather, so don't expect the same volume as adult sulfate shampoos. Daily use is fine for active children who get sweaty or dusty; the formula is designed for everyday washing and rinses clean without buildup. If the hair is very dirty (e.g., after a day at the beach, sandbox, or sports), the source notes you can repeat the application once. There's no need to leave it on — lather gently over the scalp and along the length, then rinse thoroughly with warm water until the water runs clear and the hair feels "squeaky" but not rough. Overusing product won't clean better and just makes rinsing take longer. Store the bottle upright, cap closed, away from direct heat; the 350 ml size typically lasts 6–10 weeks with daily use for one child.