Try to keep your baby awake during the day. He/she may be cranky, but if your baby sleeps a lot during the day, start keeping him or her awake more. Also, as the above person mentioned, find a night time routine. At 7 PM each night, I give my son a hot bath with sleepy time bath wash and lavender lotion afterward, I read to him, and then I nurse him to sleep. :)
Around the time u want ur baby to be sleepy just do things that will put him to sleep. .. such as a hot bath with bath time baby wash.. feed ur baby something that will make them full