I highly suggest a book, titled "Solve Your Child's Sleep Problems" by Dr Richard Ferber of the Boston Children's Hospital Sleep Clinic. It discusses many types of sleep issues, and will be useful through adolescence. I used it when it first came out 23 years ago, and my son kept waking and falling asleep up to 7 times a night! I've also recommended it to several friends with young children in the past few months, and they've *all* had great success with their little ones. It is not a "leave the child to cry" method, but a simple tactic that trains the child to soothe him/herself... there is some crying, but it allows you to check on them, they don't feel abandoned, you can see they haven't made themselves sick, and it works in just three days for most babies. (in a nutshell: ritual, put child down, child starts crying. You say "sorry, but it's bedtime. time to go to sleep...and leave her crying for 5 minutes (by a timer! no cheating.) -Go in, no lights, no picking up, no fun. Just pat her back and say "Sorry it's bedtime, time to go to sleep", and walk out again. this time wait 10 minutes before checking. same thing, then wait 15 minutes, and go in every 15 minutes, until she falls asleep. If she wakes during the night, start with 5, then 10 then 15, again. The first night is the worst. The second night, start with 10 minutes, then 15, then 20. There should be a lot less fussing. The third nigt you start with 15, then 20, then 25... the fourth night, most often if you've kept to the form, and not given in and gotten all involved in rocking or anything else that makes her think she's going to get some fun... mine snuggled right down and went to sleep with just a grumble or two)
I'd also suggest (along with the rituals that are standard for going to bed) that if you get the child a blankie...get two or three. Then, two can be in the bed, and one in the washer, and you can switch them out, without there being that interval where it doesn't smell or feel 'right', and they get upset. (They wear out so quickly, and once time has passed, the same styles are rarely available again.)
Your rocking ritual can be translated into reading a picture book to her after bath and jammies, then as she gets drowsy, into bed, goodnights, and lights out.