For self-study? With how much time on your hands?

Audiobooks are okay. Pimsleur and the like will drill basic phrases into your head and the exactly proper way to pronounce them like a native, but they are inherently limited. Michel Thomas's method is excellent for getting you to intuitively string together long sentences, but you'll again have a limited vocab and range of things to say in the end (I went through his entire German course and I don't think he once covered "Excuse me," though I could be thinking of a similar simple phrase - you get the idea though) If you're not too conscious about purloining these things, they can be found on the internet in .mp3 form via eMule/torrent and the like.

Knowing what's important to know is a big deal. You can waste your time learning the name for every animal in the zoo, but it's not going to be particularly useful on a tour. Numbers, nouns, simple verbs (The "501 verbs" series is excellent) are important. Travel phrasebooks specialize in this kind of thing, but they won't get your conversational skills going at all, really. A handy mix of intensive studies with vocab-builders and rapid-fire audiobooks is probably best for this.

Reading foreign news sites for an hour a day with a computerized English-Italian/Italian-English e-dictionary reference like Ultralingua will get you going pretty quickly on the most-used words and the ways they work in sentence structure by edited writers trained to speak correctly. The more colloquial a language, the more confusing to the foreigner, but this can be problematic if you intend to talk to people and understand them. For this to work in the long run, though, you have to combine it with little flash cards, working to memorize the words you see from both the native to the foreign and vice versa. I know two people who have learned all sorts of useful, frequently-used, and even unusual words this way in very little time.

Grammar is important, but is best tackled intensively only if you intend to spend a long time there. Otherwise, most simple phraseology and working your way around what you mean to say doesn't require much grammar in any language for the recipient to understand what you're getting at.

Hope this helps.