How to Fix Slippery Basketball Shoes
Keep the tread of the shoe clean and dry. Be sure to wash the sole regularly. When you notice the shoe starting to slide out, rinse the sole with mildly soapy water and dry with a paper towel.
In a pinch, you can spit on your hand and wipe the bottom of your shoe.
Use sticky mats on the sides of the court. These keep your shoes free of dirt and dust. Usually the mats are made of peelable plastic, so when one sheet is full of dirt, you can peel it off, then step onto the next sheet to clean your shoes.
Sweep the court with a large broom as often as possible to minimize dust and dirt.
Buy new basketball shoes. If there is no tread left on the soles, no amount of cleaning will recover the traction you need. It's better to invest in a new pair of shoes than to risk injury or slipping on the court.