Your baby is now at the age where she's beginning to develop a more predictable pattern of sleeping and waking. And you're at the stage where you're finally getting a little more sleep! Talk to her, bathe her, sing her a song and tell her a story; now is a perfect time to establish a soothing night time routine that will last for years.
Between the ages of three and six months, your baby will start to be able to sleep for long stretches at night. She is now at a stage where her 24 hour clock is beginning to understand the difference between night and day. This makes it a perfect time to help her understand a night time routine. If you haven't already, start creating a familiar sequence of calming events that unfolds night after night and clearly says, "It's time to settle down and go to sleep".