Have a schedule and a set bedtime routine. Make sure that after dinner your child engages in quiet activities instead of running around or getting worked up before bed. It's also a good idea to not to let them watch TV in the evenings as well.
I would also suggest cutting down on the fluids given before bed so that your child's sleep isn't interrupted by the need to have to go to the bathroom. You might also want to consider not giving your child anything to eat or drink that contains sugar or artificial colours with the exception of a small amount of fruit for dessert for example.