Because daddy long legs fall onto water, your initial approach should be dry fly tactics. There are any number of daddy patterns and they all work well. Given a light breeze, we prefer a buoyant, high riding fly as this is how the natural will sit on the water.
Usually, it’s a case of seeing a splashy rise and dropping your fly in the immediate area. The occasional tweak doesn’t hurt now, as this mimics the natural, which will kick and shudder at the surface