I would agree with AJATT guy personally, so i would recommend taking a quick look at his site, read/write/listen then speak, like Nagoyankee said if you try to speak first you'll end up relying on Romaji which is what happened to me the first couple of days.
As for what to read, and where to get sentences it's just common sense really, i would suggest googling things your interested in on
Japanese Google thats what i do atleast.
I can't understand it all but even if it just gets me trying to read kana and kanji, and even if i can understand a sentence here and there then it's a good thing.