You'll need to decide what makes the most sense for your business. You could offer post-dated cheques, automatic payments from a customer's bank account, or even credit card payments. The key is to be sure how much the customer will need to pay each month when the payments are due and what happens if a missed payment. You'll also want to ensure that you have a written agreement in place that both you and the customer sign. This will help avoid any misunderstandings down the road.