That depends. If you're interested in just conversing, then go and learn how to speak first, and study books that use romaji. The first time I went to Japan (in '98, I was 8 at the time) I didn't know how to read OR write; I could only speak, and that was help enough. If I didn't know what things read I'd ask my host family.
@ DarkRoseofHell: Motto benkyou shitai nara koko ni kite ne! ^_^ You should switch the order of "Nihongo" and "sukoshi" ; that will make it more grammatically sound.