Step 1: Determine Your Goal

Do you want to be able to basically greet people and conduct simple transactions in Spanish, like maybe if you were going to a Latin American country just for a few days or weeks, OR are you going to devote years to gaining complete native fluency? You should determine what you want first. Also, how long are you willing to devote to working on it? What's your time frame? Do you have a few weeks or a few years?

Step 2: Get A Home Study Course

There's just no getting around the fact that if you're serious about this you're going to have to spend some money on some educational materials, and your main tool, the one you'll learn the most from, is definitely going to be a good quality home-study course. Lot's of people like Pimsleur, but my personal favorite is Synergy Spanish (click here to see their site); in my opinion they are the best choice for someone who just needs to get to a basic level of proficiency NOW--if you just need to be able to handle simple day-to-day conversations, interactions (directions, greetings, etc.), and transactions (ordering food, buying things) in Spanish and you've only got a few days or weeks to do it, then I highly recommend Synergy; it's only $49 and has 68 lessons of 10 minutes each so you can easily complete the whole course in a week or so, maybe even a few days depending on how hard you want to work at it. I've also used Platiquemos (great if you've got an hour a day to devote for 8 months), Michel Thomas (a French man trying to teach Spanish in English--just doesn't work, can't stand his voice), and Rosetta Stone (WAY over-hyped junk, sorry, it just is).

Step 3: Find a Native Speaker to Converse With and JUST HAVE FUN!

You don't want to set up any type of formal lesson because that won't help you as much as just sitting down and speaking with them normally using colloquial day-to-day speech, because THAT is exactly the kind of language you're going to need to use when you go to a Latin American country to handle simple daily communication needs so therefore THAT is what you should be practicing--makes sense, doesn't it?

If you don't have a friend who is a native Spanish speaker who can help you, then there's several websites out there that connect people globally who are trying to learn a language so that they can help each other; I personally use a site called Friends Abroad. The idea is that there's going to be people from Spain and Latin America on there who want someone to practice their English with and in exchange you can practice your Spanish with them--I highly recommend you use a free VOIP service such as Skype so that you're not just writing with email and chat.

Step 4: Dictionaries, Thesauruses, and Translators

Personally I like to use Wordreference.com for my online Spanish-English dictionary, I used Urban Dictionary to look up spanish slang and curse words (they're better than anybody for this), and I use Babelfish for my translator. You might also want to grab a paper dictionary and a wonderful little book called '501 Spanish Verbs' that has the most commonly used verbs and shows their conjugations, very helpful.

Step 5: Learn at Least ONE New Spanish Word Each Day--You MUST Commit!

Commit to learning at least one new Spanish word per day. I like to use a site called Spanish-Word-A-Day who will gladly send you a new word to your RSS feed or to your iGoogle homepage--I know there's other sites that can also email you a new one(s) each day as well. The important thing is to commit to actually doing this, that way if you don't get any other Spanish work done that day then at least you still did SOMETHING if you've done this, and it really doesn't take but a few seconds.

Bonus Step: Watch Telenovelas! (Spanish language soap operas)

One of the best things you can do to improve your Spanish is to sit down for 30-60 minutes each day, in addition to your regular lessons (remember: you have to be committed to this!) and watch a Spanish language soap opera, called a telenovela, which will almost always be available if you have cable or satellite. Personally, I find the best thing to do if you have Tivo or something similar is to turn on subtitles (Spanish not English) and then after a character says something pause it EACH time and figure out what they said, then repeat it a few times to yourself until you've got it and could understand it if you heard it again at full speed, then unpause it and continue to do this. You might only get through 5 minutes worth of the show in 30 minutes, but you will learn a LOT of Spanish.