It's not what you say, it's how you say it...
How you communicate nonverbally is very important, and it changes drastically depending on where you are and who you're talking to. Between English speaking countries like the UK, the US, and Australia, our nonverbal speaking habits are quite different. But don't worry. It's easy to pick up on other cultures' communication habits, and you'll have their customs down lickety-split
Careful how you use your hands
We use our hands a lot to communicate (just don't get handsy). When travelling it's easy to forget that these hand signs can have very different meanings. For example, in the US we give the peace sign both with our palms facing outwards and with the back of our hand facing outwards. Former President George W. Bush made the sign with the back of his hand facing out while in London, and it did not go over well. Make sure to read up on what hand signs not to use while out of the country!