The general consensus is that the witches are most typically seen close to the woods, so you might have the best luck around those lake waters. Notably, there:

— you sometimes see shadows or hear rustling in the forest, as if something is watching

— there is a sense of static magic, the atmosphere is magically charged, although there is no curse or magic that bites or seeks to cause damage

— villagers say that the ladies of the lake often appear as silhouettes of smoke, either on boats or floating above water; this has contributed to why they have struggled to identify them — they cannot see their faces

— at the very periphery of land territory near water areas where the witches have allegedly been sighted, they can find traces of exceptionally barren, cracked, lifeless ground — very small stretches, think no more than a few palms' width and length. As Hermione and Wei Wuxian were present in Arc II, they can safely identify this looks like ground after it has been touched and travelled by the Huntress

— Miang-Si wasn't literally seduced, to be clear! She has refused to say where she made contact with the witches; the villagers fear that many ladies of the lake actually live within the village, masquerading as normal villagefolk, and that Miang-Si was approached and corrupted by such matrons