If you're taking the 5:01 am train to the airport, don't panic when the main entrance is closed. There's a side entrance to the left that is open near the taxi stand.
If you're looking for free wifi, sit or stand around the square cutout leading downstairs to the metro. Next-mesh or City Center; useful but since the signal is weak move around to catch it.
Install the VR app on your phone to purchase and access your tickets, fast, comfy and modern trains go to nearly all parts of Finland from here, very good service.
Use automatic ticketingoffice; they have English menu & it's easy. Round way ticket is cheaper and is valid for twice longer time; it can be used for any public transport when valid as well.
If you need to go to Leppävaara, take the A train. It goes from last platform. The most on the left side. You dont even need to go inside the station. It is faster.
A main landmark and focal point of public transport in Metropolitan Helsinki. Used by 200,000 passengers daily. Point-of-origin for all local VR commuter trains, most VR long-distance trains. Underground you'll find the Rautatientori metro station, the busiest in the Helsinki Metro.