Since most Finns under 50 speak excellent English, there’s no need to worry about learning Finnish in advance; a good thing, since it’s one of the world’s most unique and difficult languages. Still, as in most places, using a few words in the native tongue will endear you to locals:
Hei (pronounced just like our “hey”) is hello,
moi (pronounced “moy”) is see you later, and
kiitos (pronounced “KEE-tose”) is thanks.