When shopping online, be sure that you're buying leggings in your correct size; a pair that's too tight will stretch and tug as you move, increasing the chances of it being see-through. Before you click to purchase, double check any sizing information (as it varies by brand). Also, choose options that are made for physical activity as opposed to fashion purposes—their thicker, more durable material makes them less likely to be see-through. Then, once you have your new leggings, try them on and move around in them. If you can see underwear lines, colors, or patterns when squatting and stretching, your leggings are see-through.