Instead of folding and placing leggings in piles inside a drawer, use drawer storage boxes with dividers. These make it easy to keep leggings separated and allows you to easily see what you have to wear.
If you have ample closet space, hanging is a great option for storing leggings. Multiple tier leggings hangers allow you to store up to 8 leggings on one hanger.
Rolling leggings is a great option, especially if you're limited in space. You can find honeycomb dividers to use in drawers or utilize vertical space with storage hangers.