First, my husband had to demolish the existing paneling and dropped ceiling, and then demolish and widen the doorway. Then he updated the seriously inadequate lighting situation (which involved learning to wire a somewhat complicated three-way switch) and the outlets.
Next, he had to frame some walls to accept drywall instead of panelling, and fix all of the rest of the existing framing which was not really ready to accept drywall either.
In October, my husband and his brother updated all of the insulation in the sill and insulated the walls. My husband insulated the ceiling himself. He says that this was the most miserable part of the whole job. It was difficult to cram the batts past all of the existing obstructions. We did this mostly for "sound proofing" reasons. There are high-tech products that I'm sure do a better job, but we couldn't afford them.
In this photograph, the room has been "professionally" drywalled (I've never seen such a mess in my life) and has been painted.
The red floor consists of "garage tiles" that have a channeling system for water beneath. In a past "500 year" flood, we had some seepage of water in two locations. We have since adjusted some grading and painted the concrete block with dry-lock. We made it through a second (!) "500 year" flood without incident. Just in case we decided on this "sub-floor" system, studded the walls an inch away from the actual concrete block, and ended the drywall three inches above the floor. Nothing that can be water damaged actually touches the walls or floor, and we will use vinyl baseboards.
This isn't our intersection, but the next intersection over from ours, several days into the flood. this is usually a three-way stop...for cars, not boats. This spot is 1/3 of a mile from our house, you can see why we have taken precautions.