Sometimes all you need to do is switch up your accessories. If you own a sheer dress, wear it with a more casual belt, and flat sandals.
If you own a maxi sheer skirt, make sure your top is more on the casual side. Even pairing it with a James Perse camp shirt, Love Quote linen scarf, and flip flops will instantly create a casual outfit.
If you own a sheer blouse, wear it the boyfriend jean or a bermuda style short.