Dear self, I know you forget every time, so here's reminder #134792. I think there are a few of these reminders as posts on this journal already, too.
1. Your first drafts are pretty bare, and that's okay! Don't sweat it. Conversations and actions in a void, just roll with it. Blank room syndrome, let's go.
2. Of course it seems flat when you reread. The solution isn't to add unnecessary action or vague plot, at least not as a first port of call.
3. Start with ANCHORING the scene! Visualise it! Where are the characters? What are they wearing and doing while speaking or doing the stuff that needs getting done? Can you add any sensory descriptions beyond visual descriptions? What scents surround them? What time is it?
4. As you are rediscovering today for the 358935893th time, this already helps a lot with making scenes more vivid and flow better.
For the cursed witch, during early revisions I literally wrote "ANCHOR!" at the start of every chapter I was annotating so I'd actually remember to do that when making the changes afterwards.
But I forgot again, and was being all sad at the flat fic first draft I pulled out this morning. Now I have ANCHORED and VISUALISED the first scene, and I'm a bit less sad :D And also, having fun. Whee! \o/