need to learn how to sooth themselves and the younger the better. If you know she does not need to be fed or changed, is not sick or in pain, then let her cry for a short period of time, i.
e. 5 minutes. You can then check on her, even pick her up, but put her back in the crib awake, and leave for 10 minutes. Gradually increase the time periods, and you will be amazed how well she'll do.