Taking a deep breath, I fluxed the first two or three ties, held the outside rail down with a probe and soldered it in place. A quick poke with the probe confirmed it was held fast, and I could see it wasn't a cold joint. Flush with success, I pressed on. Flux, solder repeat.
I filed useless angles into the ends of three rails freehand before I got the idea to cut a jig to hold the rail an the correct angle. All I have to do is concentrate on holding the file straight.
My first frog.
The soldering work is more than a little messy because I've never seen this done before and am working out the kinks as I go.
For instance, I knew that the two kinds of solder I had in my tool box melted at different temperatures, but I had no idea why that was significant until I tried to carry a bead of solder to the rail while the iron was too hot for it. The low-temp solder falls off a hot iron; the high-temp solder sticks to it like cookie crumbs to a toddler's face. And I figured that out how? I grabbed the high-temp solder by mistake.
To give the first coat of cream a bit more strength, I thought I'd try a primer coat of white, applied around the windows of this coach. The results below: one coat on the right, two in the middle, three on the left. I honestly couldn't tell you if the game was worth the candle. 
Here's one weird thing about painting this particular coach: I ran across a patch of plastic where the acrylic paint turned instantly to sludge as I applied it, making a smooth, even coat impossible. I scraped it off and tried again with the same result. I've never seen a reaction like this, but then I've never used acrylic paints on plastic models before.
