I recently came across this topic on languageholic.com, and I decided that I’d address it as well. A lot of people say that you shouldn’t study two or more languages at the same time, because you’ll start confusing words. But you should consider this: I studied Spanish and Italian (and still am) at the same time, and I have yet to say something, “Voy a parlare sulle mis viajes in Europa.” (If you don’t take either language, this is a mishmash of both languages.) Ordinarily, you’d think Spanish and Italian are so similar (and they are) that it’s more likely that I’d start mixing up the two languages. However, in my mind, the two languages are rhythmically different, and so they remain separate. Moreover, as languageholic says, temporally separating the study of the languages helps as well, although I didn’t do this intentionally.
Another tip for studying multiple languages at once is keeping your notes separate. Don’t put your Catalán notes with your Spanish notes. That will get you confused, because the two languages are not only similar, but you might also start reviewing the wrong things for the wrong language.
It also helps if the languages you’re learning aren’t related. You could hypothetically learn Hindi and Mandarin Chinese at the same time, and because they’re from completely different linguistic families, you’re less likely to mix things up.
Another strategy that I found useful while learning Italian and Spanish is keeping a journal. One side is in Spanish and the other side is in Italian. This helped me visualize the difference between the two, because they were both on paper and I could compare them.
However, I don’t recommend learning more than three or four languages at the same time, although I prefer to stick with two. This is almost purely because of time devotion. I believe that you should devote equal amounts of time to the study of both languages, and it can get to be too much if you can’t do that.
So, that’s all I have to say about this. Please leave your comments! I’m curious to hear people’s thoughts on this.