Some time ago I added some thoughts on Anki (flash cards) here which might be pertinent:
If you’re serious about learning the language, I think Duolingo is a good tool. It gets a bit of a bad wrap sometimes for teaching you really random sentences, but in my opinion that is part of the benefit: you learn how to put sentences together, rather than just memorising “travel” Spanish/German/whatever. I came to it after learning a bit of Spanish, and from memory it’s instructional materials weren’t brilliant, but if you find that to be the case you might be able to supplement that part of it.
And, not software-related (and might not be relevant to you but perhaps to someone else here), but I was reminded recently that learning Esperanto before learning your first foreign language can really help speed up the process. I read about a study where it students who spent one year on Esperanto then two on French actually progressed further than students who spent the whole three years learning French. (I might have the numbers a little messed up but you get the idea.) I learnt a little Esperanto years and years ago, as a kid, and I think it did help subsequently when I started learning Spanish. I learnt using lernu.net which I assume is still around. It’s on Duolingo now as well.