All this advice here is good advice.
I learned Spanish with these things: A grammar book, a dictionary, a small library of books in Spanish with their English counterparts, and actually speaking/listening to it.
The grammar book is fairly easy. Just go to a local bookstore and see if they have anything that covers anything and everything - If it doesn't have a lesson on the subjunctive or a pronunciation guide, forget it. You can skip this one early on, but you'll need it once you get to a certain point. You may wait for this one if you're taking college courses, but they generally start off super basic during the first semester. On the other hand, college textbooks are usually fairly broad in their scope.
Dictionaries are easy. I recommend one that does Spanish/English and English/Spanish. Even better if it's small enough to carry around with you, and all the good ones have a pronunciation guide in them.
Books are easy to find in either English or Spanish, but well translated ones aren't too common. The Bible's the easiest and probably most accessible choice if you're Christian or an open-minded [Insert Your Belief System Here] that can read Christian scripture for the explicit purpose of learning a language. It'll do you less good if you're sitting around the entire study period thinking about your opinions on a book rather than why you're reading it. Just be sure to match up Bible versions - Don't get a New World English version with a King James Spanish version. If you don't want to go the biblical route, there's always other classics, such as Lord of the Rings and such. I have no clue how well they were translated, though, so you'll have to either gamble or find someone that knows.
Anyways, the idea is to set both English and Spanish books side by side - Read a sentence/paragraph/verse in English, and then in Spanish. Speak the foreign language while you do it, and, if possible, have a native speaker correct you and read with you. Failing that, just follow a pronunciation guide. Every single time you get to a word that you don't understand, look it up in your dictionary and write it down. This will help pattern recognition and expand your vocabulary.
And while you shouldn't substitute them for reading in Spanish, movies and shows are great sources for pronunciation and developing an accent. If you don't have a high Spanish speaking population in your area, this is your route to fluency. Avoid the hazard of watching them for entertainment - Whenever you hear a sentence, pause the movie and repeat what the actor just said.
Finally, the most important thing when learning any new language: Don't ever worry about messing up, and don't be embarrassed when you do. Laugh, learn, and move on.
I tried telling a lady, "Don't worry about it" once. I ended up saying, "I don't have a penis." It was hilarious, and I still went on to speak Spanish fluently despite feeling rather hopeless and stupid at times (I lived in Guatemala and spoke it constantly, so it was a fairly constant feeling at times). I learned to not give a crap whether I messed up or not and just tried my hardest. It doesn't really matter if you don't do it well at first - Eventually someone's going to understand you, you'll understand them, you'll tell them you're from Mexico, and they'll believe you. You just have to keep working on it.