How Do You Write for Other Artists?

When writing for other artists, do you have any particular ways you like to approach those sessions? Will you turn up with a few rough ideas, or to prefer to kind a sit down and get to know the artist in question before you start working on any music. The main thing i'm chasing in a collaboration, it's the feeling of what we're doing together, not in the music, but personally. I used to have a lot more targets, but i really don't any more now. It's just kind o like, this'll be fun. Let's do it, cause you never know.