I've tried this for five years. It doesn't work. You need to take a course. I learned more in JPN1001 than I ever did with subs.
That said, I knew a lot of words (nouns, mostly) for stuff like rabbit and newspaper (those two words thanks to PPD and the 1st Negima series respectively). And it was interesting because the new kids that had never heard Japanese were thrown off by the different rhythm while I was already used to it.
Of course, at all costs, suppress your power level. Say you're taking Japanese because you heard it was vastly different than English and you just want the mental challenge. Or something like that.