I became good friends with a guy who worked in our company's Mexico City office. A few years later, I decided to take the plunge and move to Mexico City myself. It didn't hurt that the girls I chased (including the one I eventually married) didn't speak much English.

I've now been here five years, and my Spanish isn't bad. It's important to make an effort, though. I've met people from overseas who've put in little effort—a real shame.

Moving to a different country isn't a realistic option for many people, and you didn't say where you're located, but if you're in the States, chances are there are plenty of Spanish speakers in your area. Why not talk to them?

As you meet Spanish-speakers qua Spanish-speakers, be sure to identify who'll give you "correct" advice and who won't. It's important to be able to understand and to be understood while communicating in various contexts. I've learned lots of useful things about Spanish from pedants, people who play fast and loose with the language, and everyone in between.

And there's plenty of well-edited Spanish language material freely available: es.wikipedia.org is generally decent. (By the way, wikipedia can be an excellent translation tool: when you're looking up some very specific term whose precise translation won't be found in a dictionary, try searching for it on en.wikipedia.org and see if there's a link to es.wikipedia.org) Some newspapers with online presences include http://www.eluniversal.com.mx (Mexico), http://www.elpais.com (Spain), and http://www.lanacion.com (Argentina); there are, of course, many others. Chances are decent that there are blogs that cover topics you're interested in, but be wary, as the quality of editing can and does vary considerably. Incorrect spelling abounds!

As you improve, you'll be able to read books in Spanish. My first book was a translation of one I'd read originally in English. I think this was a good idea, because I didn't have to worry about vocabulary I didn't understand. Reading Spanish-language authors in the original is even more satisfying. I'm currently working through Bolaño's oeuvre. Borges and Sepúlveda are other favorites, but I've really only just scratched the surface. (I've also read some stuff translated from third languages, such as several books by Murakami.)

As for references: The 501 Verbs series of books is useful (I have some minor quarrels with the Spanish one, but there's nothing out and out wrong, and I do recommend it). I like my Harper Collins Spanish/English dictionary; in addition to a good range of vocabulary, it has one of the best grammar references, in terms of both clarity and layout, that I've had the pleasure to see. (A minor issue for some with Harper Collins is that it has a slight focus on English as she is spoke in the UK and Spanish as it's spoken in Iberia; unlikely to be a problem, but I'd be remiss if I didn't mention it.) http://www.wordreference.com is an excellent resource. I also have a 5-way pictorial dictionary which has proven handy at times.

Eventually you'll outgrow whatever Spanish/English dictionary you settle upon and you'll want a more comprehensive, Spanish-only dictionary. The RAE's (http://www.rae.es) dictionary is considered by many but not all to be the most definitive. http://www.rae2.es is a more minimal interface to the RAE's content.

So, stick with it and have fun. Learning a new language is very satisfying and obviously very useful too.