Self-studying German

Proficient within a month is gonna be tough.

Buy Rosetta Stone and Pimsleur and an old grammar book. I self-studied French using this method for about two to three months. Recently I've been slacking, but while I was practicing everyday I could make and understand basic sentences as well as identify a wide variety of objects. When I pick it up again my skills usually return. The key is consistency. But no matter how hard you try you will not be proficient in a month. I'd say four to six minimum depending on how dedicated you are.

P.S. When I say "Buy," I mean "Download."

I've used both Rosetta Stone and Pimsleur. Your preference will be partially based on how you learn best. I've never had great retention when i learn by listening, but when I see something, things stick a lot better. Pimsleur is good for the commute to work, but i tend to drift after a while. I also find that because Pimsleur uses a translation method, by first saying something in english and then in spanish, when you're putting together your own thoughts, you tend to do it the same way and you bring in some of your english sentence structure, which is a little off when translated to spanish, even if most of the words are right. RS uses an immersion method whereby they show you pictures/words/phrases without any english translations. It's up to your brain to put it together based on context/patterns of what's on the screen. They gradually build up complexity and material is repeated often so that it sticks. I find that my retention is better with RS than Pimsleur. If you're very dedicated, you could probably do levels 1-3 of RS in a month and get by. If don't think either of these methods are sufficient on their own. You need to find someone to talk the language to. That's when you'll really strain your brain. And unless you start studying full-time, I don't think either method will get you up to speed within a month. Bring a phrase book or translator with you imo. edit: btw, I think both methods are more useful than college/university classes, which I foudn useless. Classes are too big, you have to go at everyone else's pace, and you don't get nearly enough talk time.

German IMHO is much more complicated than the Romance languages so it's best to find a German speaking province and live there for a while.

german is my native language, and i learned franch and spanish at school
i would say the complexity of grammar is on par, there are some parallels between romance languages and german grammer (e.g. the gender of nouns)
but despite of that german is closer related to english (both belong to the west germanic languages)

If you already know a little, there's probably no point to doing Pimsleur. I think Pimsleur can be good for absolute beginners but even if you do all 3 levels it isn't that much material. IMO the best way would be to go to the nearest university/college bookstore and get all the materials for 1st year German, ie textbook, workbook, audio CDs, and do all the assignments/drills. If you have enough spare time, you could probably get through 1st year German in a month. Also I highly recommend using flashcard software like mnemosyne or anki. Both of these have smart algorithms which show you a card more often if you get it wrong, and less often if you get it right, so you can easily be up to speed on thousands of words with just a few minutes a day.

+1 for mnemosyne.

i like the hipper, significantly cheaper Livemocha.com WAAAAAY better than Rosetta Stone