I've had 4 early talkers. I think the biggest thing is to listen very, very closely. Once you have recognized that they are trying to talk, there is a good chance that a lot of what they say IS a word. If you pay attention, you'll be able to decode it. Just today, dd3 (13mo) was yelling something from the chair in the kitchen. At first, I thought she was just yelling, but then I realized she was saying, "Down! Down! Down!" So, I said, "You would like down? Down, please." And put her on the floor.
My really little ones also tend to speak in phrases. They say the same things I regularly say to them. It is easy to miss a whole big thing coming out of such a little one, but they get frustrated when I don't understand. Things like "hereyago." Or, "nutherbite?" They are not speaking in sentences when they do that. To them it is just one word.
The other thing is to speak simply, and parrot, as CM said, but not correct. I slowly increase what my children hear/say when I am parroting. For example, when dd said, "Down!" I repeated, "Down, please." Stretching her by one more word...and a slight lesson in politeness. It is easy to do that with colors, numbers, etc. Baby says, "Cup!" I say, "Yes! Cup. Here is your RED CUP."
All of mine around two begin to stutter. It's like they suddenly have a lot more words, and huge complex sentences and their mouths can't keep up with their brains. It doesn't last very long, though tends to be worse when they are tired. I just wanted to mention that so that you didn't worry if your dd experienced the same at some point. The best advice I've found is not to correct, not to fill in the words, just patiently listen as if they were not stuttering. Mine have all appreciated being told it was normal and would go away soon. They all seemed a little worried and a lot annoyed by it.
The last thing I'll say is make sure that her words work. (Like when dd wanted down, she got down. In the early stage, I try to also give them what they ask.) If she tries to talk to you and finds you unreasonable or that you aren't paying attention, she'll have to go the good ole route of tantrums. She'll have her fair share anyway, but being able to communicate helps them out tons.