Hi there, welcome to the boards! Let me briefly outline the theories in the babywhisperer book. The main idea with independent sleep is that if you 'aide' or 'help' your baby to fall asleep they will not be able to fall asleep on their own if/when they wake early from a nap or at nightime. For example if baby fell asleep on boob, when he she wakes she's thinking 'hey I want to go to sleep, give me the boob coz thats what I need to fall asleep!' this is one reason for multiple nightwakings. Also, LOs get wuite heavy and u really dont want to be holding them to sleep or nursing etc!!
Sooooo I have few suggestions for you seeing as u seem keen to break this habit, you need to get rid of the night nursing, at 12 months she does not need it and if you break this habit she'll stop waking for it. Sounds hard I know but we're talking of putting in a few week's worth of hard work then its all soo worth it!
So, how do you do this? well you need to teach her to fall asleep on her own. Because she hasnt been 'sleep tranined' before I would you what BW calls 'gradual withdrawal' where you ermove the amount of dependency she has to fall asleep gradually. Let me outline what I did/do with my DS:
Have your bedtime routine, whatever that is, place LO in cot/crib and say ' night night i love you' or something to that effect. Place your hand on her back when u lay her down and if she seems settled remove it. when she cries, place your hand on her back or rub bacl or whatever works to calm her down and say 'shhh nigh night'. You repeat this unitl she falls asleep. It will take a lon time to start with but this time will graudually shorten as she will need you less and less.
HTH to get u started also check out the sleeping for toddlers FAQs, there's some very useful info