If your child is walking to school, review and walk the route several times with her before the first day. When school starts, have her walk to school with other children in your neighborhood, and preferably an adult. Always walk on sidewalks, and if sidewalks aren't available, walk on the side of the street facing traffic.
Street corners and intersections are the safest places to cross the street. Review looking both ways ("left, right, left") with your child before stepping off the curb to walk across the street. An intersection with a crossing guard is the best place for her to cross.
Finally, remind her to never cross the street in front of a parked car. Other cars on the road might not see her if she darts into the street.