It happens to even the best caches and the most carefull cachers. You might be very careful to avoid muggles but that doesn't mean that other cachers will be. Here is what I do.
Hide it off the beaten path. If you want to take cachers to a landmark or commonly visited area, hide the cache several hundred feet away from the main area of interest. Then mention the coordinates of any places of interest where you want cachers to visit in the description.
In your description, tell visitors the best times to go to avoid muggles.
Cammo the cache if you haven't already. Cover it in foilage, use camo duct tape, or spray paint it.
Check on it occasionally to make sure other cachers have covered it properly. I don't know how many times I have gone back to my caches to find them left out in the open.
If you want to rehide it in the same area, wait a while and don't put it in the same spot.