Same Shape, Different Direction

If you were able to take anything from the first and second postings on the topic of grain direction, I would hope that it would be this, wood is nothing more than a bundle of fibers and to shear it cleanly, each fiber needs complete support. Diagnosing which way will offer this support is as easy as cutting one direction and then judging the surface quality. This is a fine way to proceed and most likely the way that we truly learn to "read" the grain. However, to really arrive at the correct direction takes a willingness to not settle on "good enough" and reach for the sandpaper. I am convinced that the joy of hand tools is best experienced when they are working fast and final, plus my bottom line depends on it.
The photos above show a similar shaped cut out in two different orientations on a plank of wood. Once again, I've accentuated the growth rings to represent the direction of the fibers. As is indicated by the arrows, the cutting would proceed in opposite ways for each. This is a common occurance in chairs, where all sides of a workpiece are shaped. You can see that by cutting in the directions that I've indicated, each fiber will have the full support of the fiber next to it.
The difficult area is the overlap region where the cut is either perpendicular or parallel to the grain (in this case at the bottom of the cut out). In these areas, you can cut either direction but quickly run into the reverse grain. My strategy for such areas is to always leave a flat "landing strip" at the bottom of the curve to accomodate easy starting and stopping. I also do this in turnings, be it the largest diameter of a bead or the smallest of a cove. The flat area is essential to getting a clean cut and remains until my very last light cleanup pass, where I round it out (a light slicing cut can often confound the rules of grain direction). Good luck, be patient, and take light cuts!