Choose an evenly lit photo with a visible hairline and uncropped ends. If one side disappears into shadow, move yourself or the camera before editing the image. A readable starting photo improves the comparison.
Keep a preview when you can name the hair feature you prefer: a chin-length edge, an open forehead or a darker overall shade. If the appeal depends on a changed face or implausible hair, discard that comparison and try a clearer direction.
Choose the amount of hair you want around the face and neckline first. Keep a familiar cut for a single event unless you also want the change afterward. Rehearse the final style with the garment and real accessories before treating it as the plan.