sheldrake

I can use the language oddly, for example misuse idioms and phrases or use a metaphora that works in Finnish, but not in English etc..

A good beta would be helpful in catching that sort of thing. I do know people who were very apprehensive about writing fic in English, but found fandom a good place to improve their skills, because it can act as an excellent support structure.

I doubt I'd write RPS. It seems difficult to pull it off very well.

Yes, it can be. It's different from writing FPS, because the canon is so much looser and more ambiguous. It's difficult to know, for instance, how to get things like characterisation right. But there's a freedom that comes with that, too, which is part of what I like about it.