Hard question to answer! I can't tell you how I started because it'll be useless in this case but I can give some tips (in addition to the one metion by RicardoGtz): Sounds funny but use grammar books for children. They contain the basic rules. You can also use books for children because the vocabulary is very simple and easy to understand. Force her to repeat things again and again and again ..., until she use them without errors. That will help her to feel confident enough to go one step further. And, the best one, she must be exposed to the language the more she can. The harder the situations she's forced to deal with, the better she'll improve her ability to communicate in a foreign language. But maybe this step could be better for a near future. Hope this helps

Perdón, no leí bien tu pregunta, pero creo que de la misma manera en la que te escribí. Puedes darle un vocabulario básico. Y frases, por ejemplo, Buenos días, ¿Como estas? Encantado(a), Buenas noches, los colores y pedir cosas como agua, cerrar la puerta, bajar el volumen y cosas muy básicas, así lo podrá relacionar poco a poco con lo mismo que hace en el ingles =)

Solo háblalo y háblalo, y puedes ver muchos programas en español, escuchar canciones, etc. Y no te preocupes ahorita tanto de la gramática, aun aquí mucha gente se equivoca aun en eso. Ya luego podrás leer libros en español, tal vez uno que te guste y que previamente lo habías leído en ingles, así te será más fácil entenderlo e imaginarlo. Pero por lo que veo lo escribes muy bien. You only talk and talk, and also you can watch a lot of tv series or programs in Spanish, listen music in Spanish, etc. And do not worry about the grammar, even here there are a lot of people who make a lot of mistakes. Then, you may read books in Spanish, maybe one that you like and you formerly read in English; thus, you could understand easily and also imagine the things and the words. =) take care a lot, =)