Look up OB meds in a med book when you se them being given--memorize side effects and nursing interventions
Bring a pocket book on OB and read it when not busy--look up any procedures, etc (I like the Peds/OB pocket notes--it is easy to carry and has all kinds of info in it)
Ask a nurse, IF she has a spare moment, to explain a strip to you or a procedure. You will learn a ton by watching ANY nurse hang meds, start IV's, check a patient's cervix or fundus, hook up a TOCO monitor, etc, etc
Watch closely how the nurses do a head to toe assessment on a laboring woman and a newborn baby--take some notes
Bring a small nursing diagnosis book and look up diagnoses pertinent to the patients you are observing--come up with some interventions
Take notes on all you see and write out questions to ask your instructor
Then at post conference, share what you have learned and blow everyone else away!
Bring some notecards for backup study in case things are slow and you can study for a test!
I LOVED OB and you can learn so much by watching. Have fun!