I am a native English speaker. I also learned Spanish in high school and it was my second major in college. Since then I have picked up bits of Korean (lived there for 7 months, was married to a Korean-American) and French (watching movies, casually using DuoLingo). Aside from the actual course work with Spanish, I have never set out with any kind of regimen to learn a new language.

I am now thinking I would like to try and become proficient in either Arabic or Russian. These appeal for a variety of reasons, not the least of which because I have friends with whom I could try and converse if I started to pick them up.

What methods/courses/apps have any of you used to learn a new language? Any suggestions or critiques to offer on your particular method?