Croatian language
Most people in Croatia understand English, they are just a bit hesitant to speak it. If you master the basic greetings and a few phrases they will be more inclined to talk to you in English. I think they just don't want to sound silly, but if you have tried some Croatian and sounded silly (which you will), then they can try too.
One of the most important things to know, because you will have to be able to read names of things even if you don't understand what they mean, is that things are said as they are written.
Look out for the j which is pronounced like a y (y in yellow not an ee sound like in pretty). A lot of words (especially towns and places) end in a j, rather ignore it when trying to pronounce the word. An actual j sound comes from a letter that looks like a d with a line through it. đ
The other different letters are the c's. There is one with a cp over it (ch), one with a line over it (tsa) and just a plain c (also pronounce as tsa - there is a difference but my tongue doesn't do it and everyone seems to understand as long as you differentiate between ch and tsa. A c is never pronounced k.
The there is a s with a cup over it and that is pronounced sh - very easy. There is a z with a cup over it and that is said like the s in measure.
You can find plenty of guides online for how to pronounce the Croatian alphabet but don't get too bogged down. As long as you try, it is appreciated.