Thanks everybody. I took all of the advice into consideration and ran some tests this evening. Looks pretty promising, although there are a few creases to smooth out yet. I liked the technique Ascension suggested the best. Only problem was that the strokes ended up overlapping all over the place. I had to paint every contour layer to the edge of the canvas to eliminate the problem (or fill the canvas, then erase to paint in the contours). Didn't want to fill them all with white, as I wanted to keep the different contours filled with distinct colors. Anyway, this technique seems to work well, but I think it'd be easier to draw the contours lines by hand for a bigger map with lots of mountains. Or maybe it'd work better to paint from the highest elevations down? Hmmm, will try that.

I also found it much easier to do the relief shading after the contour lines were in place, so I might have to rethink the order of the workflow. I'll try some more tomorrow and see if I can figure it out better. Too late now.