For some children, letting them know in advance what to expect in a new situation helps them deal with their concerns. Don't let up on discipline and limits in order to appease a fearful child. The child needs the security of limits. Provide safe boundaries within which the child can function. Don't read more into a fear than is really there, and understand that fears may not disappear overnight.
Most fears abate with time as children discover they can cope.
They learn that parents always return, bad things won't happen because it's dark, ghosts and monsters are not real, etc. Remember that fears may appear when a child is attempting to deal with a transition or a particular stress in school or at home. A new school, a new baby, a move to a new home may trigger a re-appearance of an old fear or the emergence of a new one. But sometimes a child may show excessive fears, worry or other signs of stress, such as difficulty sleeping, undue anxiety about separation, withdrawal from new or previously enjoyed situations, or complaints of headaches or stomachaches. When feelings and reactions become too strong and out of proportion to what's really going on, and the fears interfere with the child's life, it's time to speak openly with the child to try and ascertain what he's experiencing.