There are many books written for children in Spanish. If you read them to her, and help her to sound out what's written on the pages, that would be very helpful.
If you don't speak Spanish yourself, I suggest you find someone that does.
Perhaps there's a Spanish speaker that works at a nursery.
Some children's books are written in both languages. I think those would also be good. Your daughter can then hear and learn both languages at the same time. (And those stories may also help an English-speaking reader to learn a thing or two
a la vez 
.)