Spanish is a relatively simple language. Take some
classes, learn some basics, then immerse yourself. Nothing like immersion to improve your language skills and build your vocabulary. Just some basics plus knowing how to ask the name of something ("Como se llama eso?") goes a long way to improving your Spanish.
But, be aware you will learn the dialect of where you choose to immerse yourself (and there are many regional/local dialects of Spanish). For example, I live in a
remote rural village of about 100 people, mostly uneducated, sort of like going to
Mississippi to learn English (I'm from
Mississippi, so I can say that). I realized many years ago that I was
learning "redneck" Spanish!
As others have pointed out,
learning a couple of Latin based languages (like English and Spanish) can make picking up other Latin based languages easier. I find now that if read instructions in French or Italian, I can get the general ideal.