Set your mildew-stained sneakers on top of a layer of newspaper. Position the sneakers so they're in a sunny location outside or near an open window.
Fill a bowl with 1/4 cup each of lemon juice and table salt. Stir the two ingredients together until mixed well.
Spoon the lemon and salt paste onto the mildew stains on your sneakers. Leave the shoes in the sun until the paste dries. The combination of sun and lemon paste kills the mildew and helps bleach the stains.
Brush the lemon paste off the surface of your sneakers using an old toothbrush.
Combine 1/2 teaspoon of laundry detergent and baking soda in a bowl. Stir the two ingredients together to create a solution to clean and deodorize your sneakers.
Moisten the old toothbrush with water. Dip the brush in the detergent and baking soda solution. Scrub the exterior of your sneakers to remove any remaining mildew stains.
Wet the toothbrush with water and scrub the shoes to rinse off the detergent. Dampen a clean cloth and blot the canvas to remove the remainder of the detergent solution.
Fill the inside of the sneakers with crumpled newspaper to hold the shape as they dry. Allow them to air dry.