Moi Maria! Unfortunately there is no simple answer, because the Finns don't really engage in small talk. It is more frequent to hear people comment on a specific topic to try and start a conversation than it is to hear a "how are you". Talking about a specific topic might be difficult if you don't have anything else in common with someone other than that you both, say, live in the same apartment building. That's why a full conversation between two neighbors meeting in the hallway is often a short and snappy:
I personally like to express my interest and/or ask a question on something I think the other person might be interested in. The caveat above still applies and if you know little about the other person, you may not have much to work with.