A couple weeks ago, I set forth to turn the cobbled-together hunks of sheetrock into legitimate bathroom walls with a roll of fiberglass mesh tape, a 6-inch taping knife, a 10-inch taping knife, a corner knife (borrowed from Uncle Keith), a huge bucket of joint compound, and a head full of drywall "mudding" tips (also courtesy of Keith).
I was prepared for some seriously patience-taxing work, especially since I'd never done this particular task before (though the tedious nature of it definitely felt familiar). First I taped all the joints with the mesh tape. Next, I used the 6-inch knife to scoop mud out of the bucket and apply it liberally along the joints. Then I went back with the 10-inch knife to spread it out as wide and flat and smooth as I could. After about 24 hours of drying, I attacked it all with sandpaper, wiped the dust off with a damp sponge, and started again. The second time, I applied the joint compound in a much thinner and wider layer. After more drying and more sanding, I evaluated things. Surprisingly, most of it was looking much better than I'd thought it would.
There are certainly some spots here and there that will need at least another coat, but I would say that most of it needs only another light pass with some fine-grit sandpaper before it's done.
(Progress on the ceiling part, small as it is, is lagging behind; the joints were very wide and uneven, so it has taken a lot more work to get it close to acceptable...not to mention that working overhead is about five times more difficult than working at eye level.)