For both straight and curved paths I lay out one side with a garden hose as a guide, then align the round edge rocks along the hose. This makes for a smooth guideline even if the rocks are somewhat different in size. Remove any sod or loose organic material, then lay down landscaping fabric. The fabric doesn’t make the area weed-proof forever, but it does a good job separating the stone from the soil below. Without it, the crushed stone gradually sinks into the ground, especially in damp spots.