do it over a flat cushion or something else that the screw won't move around on if dropped, because if it gets on the floor you'll never find it
That's good advice. I routinely repair and do maintenance on fishing reels that are loaded with small screws and springs. Here's a tip in case you do drop that small screw: If you turn on a flashlight and lay it on the ground so that the light shines almost parallel to the floor, anything in the light's path will cast a big enough shadow to be easily seen.