One thing I had to do before the appraiser came was temporarily fix this one terrible looking wall downstairs. The wall used to have stained tongue-and-groove pine boards over drywall. Unfortunately, the panels were screwed in from behind the drywall - an area that the previous owner later finished by drywalling the interior wall. This meant you could only remove the panels by ripping the screws through the drywall.
As you can imagine, that made a huge mess of the drywall.
I decided to pick up two sheet of 1/2" drywall and put them over the old drywall, using screws and construction adhesive. This would also be a great place to practice drywall taping and finishing, as I'll need to replace all the drywall in the kitchen as part of this wallpaper (see entry about wallpaper) This is really just a temporary fix for the appraisal as I intend to open up those stairs and use wainscoting on that wall. That will be likely the last part of the renovation.
Proper taping of drywall is much more exacting than it looks. I made a few mistakes, but overall I was extremely pleased with how the job came out. There is no hump in the middle of the wall, and none of the screw patches are visible. I did have a problem with some tape bubbling up due to an insufficient first coat, but it settled down later. My best advice is to get a 12" taping knife, do the job in three coats over three days, and make sure you always smooth with the knives so little sanding is required later. I learned all these from this excellent book. I can't recommend that enough.
The first photo is the new wall screwed and glued to the old. The second photo shows the job after two coats of Kilz primer.