As well as the language, which as Ian says is hugely important, don't forget that as well as your home-related bills such as rent, fuel, transport etc, you will also have the €300 monthly autonomo fee (assuming you will be self-employed) regardless of whether you have work in that month! Yes we know it's mad .... Just warning you that for freelancers or casuals, it's a lot to find before you get to keep any of your income for yourself :-(
Not trying to be negative, but as Ian says there are a heck of a lot of Spanish folk looking for work - you need either specialist skills or exceptionally good language skills to be chosen ahead of them for an employed post, or if you go freelance or start a business you have the monthly €300 to cover.
Good luck though and let us know how you get on :-)