My personal recommendation would be Memrise's third party 5000 word deck for vocabulary, and something like this course or a tutor for grammar.
I used Duolingo for a month when starting out and consider it a mistake. It doesn't teach grammar, vocabulary goes faster when you space repitition individual words, and even after the full tree is unlocked there isn't really that much depth.
I used Duolingo for a month when starting out and consider it a mistake. It doesn't teach grammar, vocabulary goes faster when you space repitition individual words, and even after the full tree is unlocked there isn't really that much depth.