"Repetition is the key to learning."
I've taught language on a high school level for twenty years, and I love it! Many of my current students who never thought that they could learn Spanish are conquering that doubt because they have set goals. We add a little of the language at a time.
In Chicago, my students all spoke Spanish as their first language. I taught them grammar from the beginning, and we studied Reading everyday. The reading comprehension practice built their vocabulary. Of course, the mandatory English conversation is what causes the vocabulary to solidify; the thinking process in English eventually surfaces.
I've traveled to several Spanish-speaking countries in the last decade, and there is a great desire to speak English. One thing holds people back, and it is fear. Don't be afraid--take that giant step! In Brazil I taught Portuguese-speaking adults how to speak key phrases in English to function in a business environment, and I didn't speak a bit of Portuguese. It was successful because we communicated very slowly and OFTEN. Writing things down and learning how to spell is important,yes, but it is the oral practice that makes the difference in climbing through that window of THE LANGUAGE BARRIER that scares people.