Create a wind-down bedtime routine: a schedule of activities that will be the same every night and will become a ritual. For example, your child gets to pick out two books that you read to her, then you hug her and her teddy bear, then you say goodnight and turn out the lights. Come up with a routine unique to your family and your child.
The earlier you start a bedtime ritual the more effective it will become. If possible, you should go through your ritual every night. Try to create rituals that are manageable in all settings and not too elaborate.