This girl has not chance of successfully bending over.
If you can see through them, wear them as tights/ with a dress.
This is a great option in sub zero weather. Target, Mossimo Brand leggings are great for this purpose.
This option from J Crew is a safe bet!
As a tip, when you sit down in the dressing room and can see the whites of your knees, the leggings are too sheer and should be considered as tights.