How to get baby to fall asleep without being rocked..

So I rock her until she's sleeping and quietly put her in her crib. Well the past two weeks have been horrible. As soon as I stand-up she wakes up and starts crying. Do I just put her in there and let her cry until she falls asleep? Should I start putting her in her crib without rocking all together? I'm pregnant and due in September. My Husband works long hours so I'm always putting her to bed. I'm afraid that new baby will need me while I'm rocking her to sleep so I want to start training her to fall asleep without me... I'm lost and need help.