During preparation, you are allowed to take as many risks as you need to, improv the hell out of your script, see where it takes you. Read it out loud, say your lines out loud with the choices you made. And eventually it should just feel right. It would feel so right that you don’t have any doubts about it, the risks no longer feel like risks. But this process takes great effort and tremendous energy.
There is a trick that I understood, a trick, not a full proof technique, but a trick; though now that I think about it, it’s not a trick but a requirement in the process. You are giving your partner a stimulus for them to respond either by saying their lines or doing something. At the same time, you are also responding to their stimuli.
Trick: If you breakdown your script into, what stimulus am I getting in order to respond according to the script, and what stimulus does my partner need from me to respond according the script. This should help speed up the limbo phase between script analysis and scene preparation. Take risks to feel it just right, while preparation. And during your scene, listen to your impulse and you might start to listen and respond to your partner with relative effortlessness (depends on how much work you put in).
Note: I may realize in future that this may or may not be proper, and I will update accordingly.