It depends on the age and type of child's personality. First pray for them to follow the path through the will of Christ.
If they are a teen, it's the most difficult mostly. As teens tend to tune out or ignore/forget. If this is the case, just be a beacon of Christ for your child to find attractive to follow. Explain to any questions or negatives they ask or say. Don't go the "you'll burn" if you don't believe, route. More of a, reason why it is better to follow than the alternative. Teach the lessons of the good versus negative if the chance arrises, but not in arguments. Curiosity answering. If you don't remember or know what the positive/negatives are, read more of the word. If you can answer any question they ask and calmly, they will think about it. In argument, they will still or get angry.
If it's a young child, just gently ask questions. Not too many at a time. One or two doesn't confuse most, as long as it's explained in a simple way. More activity for them with other Christian children may help.
With adults, as long as you can talk about God etc, just have a slow, not heated conversation. Explaining the why, why not, benefits of following Christ.
Knowledge of the word of God helps your maximising of positive results from God.
Though I don't have much experience explaining anything, except through writing. As I'm single and not a pastor etc. So take what you think is right through God.