Hello.. I know pimsleur has a pretty good language program for Croatian and in most guide books they will have some words to know and things like that. But in actuality I don't think you need to worry about it a whole lot. I know some basic words in Croatian but rarely do I have to use them. Almost everyone we have encountered in restaurants, hotels, etc know how to speak English. You might get into trouble if you are renting from someones house but otherwise I wouldnt worry about it.