Working outside of my comfort zone.
I have a basic structure in mind for this -- it's something relatively short and I think I know most of the actions that have to happen. But each individual scene doesn't have a shape yet. Generally I need an ending before I can get comfortable with the rhythm and the depth of detail and the places to deviate. If I know the end it's easier to know when I'm driving toward it and when I'm faking left.
Accepting now that I don't know any of that now, today I just started writing what I do know. In the middle of maybe six scenes. It's a little like doing a jigsaw puzzle and taking the pieces that are definitely people and definitely faces, and leaving the blue sky for later.