When one decides, the other has to discover.
We don't like to be too creative on stage. Being creative implies making too many decisions as actors. Our characters should of course be making decisions all the time, otherwise we keep on stalling the story, but we as actors should be as much in the moment as possible.
However, obviously we sometimes make conscious decisions about things in the scene. We can choose a character from the onset, imply a location in a line of dialogue, have a general idea for an offer to make.
In all of these situations, it is very important you remain fully aware that your decision still has to be discovered by your partner. Leave the time and space for that to happen. Don't jump to the next thing right away.
Keeping this in mind prevents us following our own path in a scene, which risks our scene partner to be left behind in the dark... Take care of each other!