You can include a clause in your terms and conditions stating that the goods remain your property until paid for. Like other terms and conditions, this only applies if the customer agreed to your terms before the sale was made.
A retention of title clause like this might say that you are entitled to take your goods back if the customer hasn’t paid by the due date. Obviously this can be problematic if the customer has sold your goods on or processed them, or if the goods are perishable.
You should take advice on what to include in your terms and conditions, or if you want to try to enforce a retention of title clause.