Spend even a few days moving around Helsinki and you will start noticing the same short Finnish phrases again and again -- on the tram, at the kauppahalli, in a small kahvila. Here are five worth learning first, straight from an independent, free course for anyone picking up Finnish.
1. Terve!
A relaxed, all-purpose "hi." It works with a shopkeeper, a classmate, or a neighbour in the stairwell -- friendlier than a nod, less formal than hyvää päivää ("good day"), which you will still hear from someone older or in a more official setting.
2. Kiitos
"Thank you." Finns use it constantly and briefly: after the bus driver opens the doors, after a barista hands over a coffee, after someone holds a door. A quiet kiitos goes a long way, and kiitos paljon ("thanks a lot") covers anything bigger.
3. Anteeksi
Both "sorry" and "excuse me." Say it to squeeze past someone on a crowded tram, to get a shop assistant's attention, or to admit you stepped on someone's foot. Context does the rest of the work.
4. Paljonko tämä maksaa?
"How much does this cost?" Handy at a market stall, a flea market, or a kiosk where the price tag has wandered off. A shorter paljonko? on its own, pointing at the item, is perfectly understood too.
5. Nähdään!
A cheerful "see you!" for wrapping up almost any conversation -- classmates after a lesson, new friends after coffee, neighbours on the stairs. Moi moi works the same way if you want something even more casual.
None of these need perfect grammar to land. Finns are used to hearing short phrases from learners, and a friendly terve at the start of a conversation goes further than a perfectly conjugated sentence.