I have struggled with learning Spanish, mostly on my own, for a number of years. I know there is no substitute for immersion for really learning to speak another language fluently, but lacking the time and money to do so, I have tried a number of things.
I started with a set of cassettes from a Diplomatic course that wasn’t particularly helpful except for learning pronunciation by mimicry. Then I tried a wonderful course by BilingualAmerica.com. The in-house and personal lessons by phone were too expensive, though, so I purchased the first 3 levels of the Spanish Power self-study CDs and lesson books. Their system of learning is excellent for attaining a basic vocabulary, sentence structure, grammar, and verb conjugation. I quickly learned that I needed to work on my verbal skills, so I signed up for some reasonably priced night classes at a local language academy. It was a big help and a lot of fun, but unfortunately the academy went out of business. So now I am back on my own, although I occasionally find a Spanish Meetup group that is helpful in practicing conversional skills.
Self-study of Spanish grammar and other learning books got very boring and not very motivating. I bought a few dual language books where you have Spanish on one side of a page and English on the other. Such books are hard to find and are usually geared toward grade school learners. I bought a few young adult books in Spanish as well, however, looking up unknown vocabulary was time consuming and tedious.
Then I purchased a Kindle, mainly because of its ability to do on-the-spot word translations. This has kept me interested for sure. I can now find books in Spanish that I enjoy and are at the adult reading level. My latest Kindle is the Paperwhite which goes a step further. You can translate a word or a phrase. Often you will find that a single translated word does not seem to fit the context of the sentence. In such cases, you can highlight and translate the whole sentence surrounding the word and get a better understanding. With the help of people who are multilingual that contribute to the Google Translate engine, the translations are getting better and better. Reading Spanish books on the Kindle has definitely proved invaluable in increasing and fermenting my vocabulary.
I still hope one day that I can travel to a country where I can immerse myself and speak Spanish every day, but until then, reading in Spanish every day on my Kindle is enough for me.
UPDATE: Language translations also work beautifully on the Kindle Fire tablet