Know what the consequences will be before you are tested. Let the children know what the consequences are before they do the testing. The time required to avoid a problem is always less than the time required to resolve the problem. Make expectations clear and expect to repeat them frequently. If the child cannot verbally explain what is expected or physically demonstrate it, try again.
Children are new learners.
They need time and lots of patience. Any behavior that draws attention of any kind will be repeated. Don't expect more from the child than you expect from yourself. Don't act as if the child did something on purpose when, in fact, it was an accident. Embarrassment and humilation do not encourage fewer accidents.