Having mastered many other languages

, although, to be fair, English is a work in progress, I have decided to try and learn a bit of Spanish from home.
Given that I'm starting from virtually zero, I've done a few basic tests on the free Duolingo site but I'm not sure about the structure of their learning.
Has anyone used Duolingo or can recommend a better one?
I've used CD and book approaches for French and Italian. Some good, some appalling. I particularly disliked Michel Thomas' approach and would go so far as to say I'd have like to punchio his lampios out sometimes.