I reached 1 year of learning Spanish with Duolingo yesterday. While I don't think Duolingo is the perfect way to learn a language, I have definitely made some good progress. I'm now at the point where I can read some things in Spanish and often get a general understanding,although there are still a lot of words I don't know. Responding in Spanish is harder. I wouldn't be able to have an in depth conversation but I know enough that would be useful for travelling (asking for directions, shopping, ordering food etc).

What I found has worked for me is doing an average of 5-6 lessons per day (about 15-20 minutes). Less than that and I felt I wasn't making much progress, more and it is sometimes hard to take everything in.

The most important things though, which apply generally to achieving most things in life, are persistence and consistency.