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You will want a straight section of branch that has very few twists and knots. The stave will be about 5 feet (1.5 m) long, so if you cut a branch down make sure not to split or crack the wood.  Some of the best bow woods include yew, ash, and hickory. Any hardwood should work OK in a pinch. The stave should be no more than 2 inches (5.1 cm) in diameter. Hold the stave upright, with a loose grip on the top and the bottom set against your foot. Gently push the center of the stave. The piece of wood will rotate and the natural curve of the wood will point away from you. This will show you the “inside” and the “outside” of the bow. You will be making cuts to the inside of the bow, but the outside must be left untouched. Any cuts made to the outside of the bow will severely affect the integrity of the bow, and will lead to it breaking early. Find the middle of the stave. Make marks approximately three inches out from the center in each direction. This will be the handhold. Like the back, it will remain untouched to keep the tension from snapping the bow in half.

Summary:
Find the wood. Find the curve. Mark the handhold.