The predictive text keyboard on my phone has helped me with Finnish SO MUCH. There's the little benefits, like how it will autocorrect and put in all the umlauts when I'm too lazy to swipe to the Finnish keyboard. Or how it will autocorrect words that I misspell.
But the larger benefit is that it helps me become familiar with collocations in Finnish - you know, the words that people tend to use together in Finnish. If I type "mitä", the phone will suggest "mieltä" and then "olet" for "what do you think?" If I want to say "at what time [do you want to do something]" and can't remember if there are two a's or only one in aikaan, all I have to do is type "mihin" and the phone will prompt "aikaan." Two a's!
Just now I was texting someone and I wanted to say "what time would you like to come?" in a polite way in Finnish (polite ways are the death of me - I can bash out sentences but making them nice is hard!). I tried it out a few different ways, but nothing sounded right. I decided to try typing "haluaisit" to see if a) it existed and b) the predictive keyboard paired it with verbs. And I found out a) yes and b) yes. So I used it! In a way, I've decided that it's better to sound like I made a predictive text error than a non-native speaker error.
I suppose that over time, I will fill the default predictive keyboard with my own horrible Finnish mistakes, but for now, it's like having a little collocation tool in the palm of my hand.