When should I cut back my lilies, and what specific factors should I consider in determining the optimal timing for this task? For instance, is it crucial to take into account the particular variety of lilies flourishing in my garden, as some may have distinct growth patterns that influence their pruning needs? Additionally, might the prevailing climate and seasonal changes play a significant role in dictating when the foliage begins to die back? Should I observe the color and health of the leaves closely, paying particular attention to whether they exhibit signs of wilting or browning? Furthermore, could the overall vigor of the plant at the end of the blooming season provide any clues regarding the best time to execute the cutback? In light of these considerations, how do I ascertain whether there are any universal guidelines or rules of thumb that might simplify this seemingly intricate process?