If you need to be able to read, write and speak it I would suggest finding a class at a local language center or community college.
I am actually trying to learn Russian right now too! I bought several books that claim to help you learn it, and it you are good at memorization those might work for you. I ended up trying them for a week then getting lazy and not doing it. The hardest part for me was the Cyrillic alphabet.
Personally I don't need/want to read or write, just speak so I tried the Pimsleur cds. So far it is awesome! It is one 30 minute lesson a day (I listen to mine on my drive home from work).
I am about 6 days in and I can say things like where do you want to eat, I do/don't understand Russian, where is ____st, etc.
I would really recommend it if you want to just be able to speak conversationally.
Pheonix has great advice! I definitely second taking a class if you're looking to develop comprehensive skills, especially with reading and writing.
The best way to learn to speak and understand spoken Russian, as with any other foreign language, is to be immersed in it. Are you acquainted with any Russian speakers? If so, ask them if they wouldn't mind speaking with you or helping you out. A lot of the time, people can be pretty receptive.