Duolingo (free) is ok for learning some vocabulary and grammar, but not so useful for verbal comprehension or speaking.
Other than that, listening to talk radio all day (you can find "Radio 10" live online), watching argentine TV shows, movies. <-- That helps with comprehension. For actual speaking, once you have the basics, the best way is to be forced to speak it, usually because your job requires it... but if you aren't working a normal job here that requires Spanish, you have to find some common interest (maybe meetup.com) where you have to use Spanish.
I studied Spanish for two years in high school, but I had no speaking practice for over 30 years. When I arrived in BA, I listened to how people use the language here. It helped having friends who spoke no English. After three years, I began thinking in the language.
Free lessons: listening to conversation on the bus, subte, television, radio, etc. Absorb the language. Internet lessons are free.