B.R.
Reading books to her and just plain talking with her ... not 'at' or 'to' her (and that's a real subtle difference) are the best ways I can suggest.
Getting her into groups with other children near her age is also a good idea, because they often can 'feed' off of each other and learn better that way. It may be more helpful if some of the other children are a bit older and are already speaking well.
And.. remember your new little one was born about the time your daughter's speech might be expected to really take off developing. That sometimes can make a difference in how a child's speech develops. It can either result in delays or can actually result in a child's speech taking off faster.. it just depends on the child.
Above all.. remember she is an idividual, and as some others have suggested her speech patterns will not be exactly like anyone else's. We have general ideas of when and how children begin to talk, and these are wonderful help's in detecting problems if they exist, but each child has his or her own time schedule and we shouldn't panic if a child isn't on the schedule we think is right.
I recall a cousin of mine who didn't speak at all until she was about 4. They had all sorts of tests run to no avail. After she started talking, someone happened to ask her why it had taken so long, and she simply told them she hadn't had anything to say before then. I haven't seen her in years, but understand she's now a non-stop talker.