Okay, I've tried to post here two or three times now, gotten distracted and run off.
Rosetta Stone is expensive, and while I've used it, I'm not sure how to speak on its usefulness. It's immersion based. You see something and hear the word. There are no English instructions saying "This is this form, and that is that form!" If you learn well based on that intuition and you're just trying to learn conversational Spanish, then there are similar immersion based programs available.
I'm a textbook learner, so I bought myself a textbook. I did well enough working with RS, but I just enjoy learning sentence structure and things like that, and I wanted a stronger focus on reading (aloud) and writing to supplement my conversational abilities. When you're learning something by yourself, you tailor it to your own needs and interests and skills. Conversational is still important to me, so while I'm working with my textbook, I answer every question orally first, and then write down my answer.
Etc. There are plenty of resources. Free podcasts, books, etc. Most of them will probably work well enough if you find a style that teaches the way you want to learn; a textbook that works for me might not work for you (mine is very English-minimal and makes me use a lot of context clues to figure out what's going on, which I find delightfully challenging but possible, and others might find frustrating and discouraging.)