I wrote a post a while ago about some products on a site called
www.worldlanguagelearning.com which I found to be amazing. I recommend Ultra Learn and The Immersion Protocol for things I found really useful, even as a language teacher and avid language learner.
As well as studying languages and education at university, I have learned several languages by myself, and done very well at them, even though I say so myself. There are several techniques and additional exrcises (Photoreading etc) that can really help you in learning a language. One thing I will say, though, is that you do need to learn the grammar in order to be a good speaker of the language. Avoid the temptation to ignore grammar just because it it difficult or boring. A lot of courses nowadays ignore grammar and stress "communication". Of course, communication is vital, but you do not have to speak a language well in order to communicate. I suggest getting a good, functional course, such as those in French, Spanish, Italian and German produced by the BBC. Look for the type of course that teaches you language you can use but that also does not skip the grammar and structure of the lanuage. An inexpensive range of just such good basic courses is "Teach yourself". Make sure you get tapes with any course you buy. You simply cannot do without tapes. Linguaphone are also good (although pricey!) as are Pimsleur (even more pricey!), but there are a lot of gimmicks out there too, so watch out what you buy! I have never tried Rosetta Stone, although I have read a few rewiews on the net by language teachers that were non too favorable. I am not willing to spend all that money to find out for myself, although I have been tempted to go for the internet free trial. The only trouble is, you have to enter your credit card info BEFORE the demo, which I can't help feeling is suspect. Still, that might just be me!
Found one of the reviews, if you want to check it out:
http://www-writing.berkeley.edu/chorus/call/reviews/rosetta_russian/index.html
In general, what I will say from experience is that if the course or method you choose looks like it is promising you an easy ride to learn the language (Pimsleur excepted), then it will probably not be adequate to teach you the language properly and give you the skills that you want or need. People don't usually like to hear me say that because they think (as a lot of courses like to adverise) that they can "learn the language the way they did as a child", but this is my opinion based on my own extensive learning and teaching and what I have seen of that of other people. Please feel free to take it or leave it, but if you want to be good at a foreign language, you are going to have to work at it.
Hope this helps.