I think the best way to learn Spanish is to go ahead and purchase a Spanish course such as
Rocket Spanish.
I say this because although you might pick up phrases and words from reading Spanish literature or speaking with Spanish speakers, the fact is that you won't build a natural
foundation of the Spanish language by learning this way. By learning in an almost haphazard and un-structured fashion, you are only asking for a lengthened learning period and
problems later in your learning.
By starting with a tried and tested Spanish course, you'll be instantly put onto the right track by a
proven step-by-step guide. This will give you a strong basis to then build your Spanish up from naturally and cleanly.
Think of it this way - at school, you don't learn really hard words when you're only small. You need to get to grips with the basic stuff that makes up the language first in order to grow your knowledge later on. Sure, you'll pay some money up front for the Spanish course, but if you use it right - you will learn Spanish a lot quicker and a lot easier than without a course.
I hope this helps you?