Okay, here’s my take.
I build all my tracks against a straight edge and use Tamiya Extra Thin Cement.
I build a run for each side that’s long enough to go from the middle of the front road wheel to the middle of the last one and let them dry completely. This gives me a straight, firm run for each side.
Next, I build a small run long enough to go from the front road wheel to the drive sprocket and another to go from the rear road wheel to the idler and let them dry hard and firm. (I actually do these at the same time as the ones above.)
Then, I glue on a length or two between the front end of the bottom (long) run and the short one that goes to the driver and let it set for about 10 to 15 minutes. (Same for the back of the bottom run.) And let that set for a half hour or so.
Now I do a length long enough to go from the end of the short run to the driver to the center of the top of the driver. I do the same for the idler, but I don’t glue one set of links together about the center, rear of the driver. (Make sure the fit snugly together, though.) Let them dry for a half hour or so.
Now for the fun part…
Glue up runs long enough to go from the end of the run on top of the driver to the on on top of the idler plus a couple of extra links. You can do this as all one long run, or as several shorter ones that go between the center of the return rollers. Make sure you do this in about 10 to 15 minutes. Then, glue the end of this run to the on of the top of the driver and work it over the return rollers to the idler pushing however much sag you need/want between the rollers. By adjusting the number of links and the amount of sag, you should be able to mate up exactly with the run on top of the idler.
Let this all set up until it’s completely dry, then gently pry apart the unglued join at the back of the idler and lift off the track.
For painting, I flat coat the track in flat black (Model Master).
When dry, I do a heavy drybrush of Model Master steel and really work it into the surfaces of the links (including the recessed surfaces.) Let the black show through somewhat. It will be real black in the recessed corners.
Then, I use a rust wash mix of Humbrol leather and about a 3/8 to 1/2 length of burnt sienna oil paint. I do this at least two times. Often more times. Do it until you like the effect. Let dry completely.
Next is a light drybrush of Model Master silver on the high, wear points.
Once in a while, I’ll hit it with a wash of rustall (which is acrylic) and tough up the silver highlighting, as required.
Long process, but pretty effective.
Good luck.