Masks work by reducing the spread of droplets. That means if you remove your mask by the cloth covering, instead of the ear loops or ties, you're getting potentially infected droplets on your hands and spreading them around. Remove your mask carefully by the ear loops, wash it after use, and wash your hands after removal.
The easiest way to wash your masks might be to buy a week's worth and toss them into the washing machine with regular detergent. But I've also been soaking mine in my bathroom sink with hot water and no-rinse detergent, then line-drying in the sun.
Don't get overenthusiastic with the adjustable straps, either. The mask shouldn't be so tight that it restricts your breathing, and a mask is also not recommended for elderly people or children under 2.