Make sure you get NRP (neonatal resuscitation program) training ASAP. You HAVE to have this if you are going into OB nursing of any sort.
Breastfeeding is a huge part of the job, but only part of it.
You also need to learn about fetal heart monitoring, labor and delivery processes/stages and the drugs we use in antepartal/intrapartal and postpartal courses also. You need to learn about well newborn nursing as well. There are many good books on the subject from AWHONN and other companies. See above thread for a couple suggestions (sticky) Also check the NICU forum for books/materials regarding newborn nursing; there are some really good ones there.
You can learn about Fetal Heart monitoring by getting into seminars/conferences or getting some good books on the subject. Ask your manager about a basic Fetal Heart Monitoring course ASAP. You HAVE to have this.
I also recommend you get some training on how to deal with perinatal/maternal loss. Death on OB seems the most unnatural and shattering event (and it is!)---- and you have to be prepared to deal not only with the families experiencing these losses and their pain. You have to confront your OWN feelings regarding newborn/fetal death and how you will cope with a particularly tough shift. And also, although rare, mothers DO die of obstetric complications. Nothing is worse than seeing a young, apparently healthy woman develop complications and die this way. Be prepared to deal with a firestorm of emotions from the families/friends of the obstetric patient and those within yourself --- be SURE you have healthy outlets and places you can talk about these things, where you feel safe. It is essential.
There are many good books in the sticky above that are recommended reading for OB. I have suggestions regarding perinatal losses, if you are interested.
But remember, you cannot possibly get all you need from any site, including THIS one, or book; go prepared to jump in and be a sponge on the job. Hopefully, you will get a good preceptor. If you are like the many of us who did NOT, just be prepared to learn on your feet. You are fortunate in that you are an experienced nurse, so you will be able to adapt pretty quickly. You are motivated! It's like any area of nursing; experience is the very BEST teacher for which no book learning alone can prepare you.
I do recommend joining AWHONN; some bennies include reduced prices to their conferences and on their books/learning materials, a journal subscription and helping you stay on cutting edge of OB/GYN/NEWBORN nursing.
Our job is diverse in responsibility and duties. Legal pitfalls abound as OB is the most litigious area of nursing there is! The way to be smart is not to focus on just one area; you will need to develop proficiency in all to be a good labor and delivery nurse. Like I said above, be a sponge! Best wishes and come here with any specific questions you have! Glad to help!