Some businesses, such as hair dressers, need only a simple tool to keep track of upcoming appointments, and take care of payments once the customer is in their hands, so to speak.
Others, however, need to make sure that the appointment is valid, that it is meant seriously, that the customer is committing. If someone books a room in your hotel and never arrives, you lose money. That is why you need a tool that combines booking system on-line with payments on-line.
Fortunately, there are ways to combine these two. Or, rather, you can get an on-line appointment software that offers on-line payments as a feature. You want to look for on-line reservation solution with integrated on-line payments: PayPal, Credit cards etc.
Make sure that you choose a system that supports all the major payment methods your customers prefers. Don’t rely just on one way of payment, especially if your customers are not used to it. Offer the type of payment you know your customers are comfortable using. You will save them, and yourself, a lot of hassle, and your calendar will fill with appointments, while your account will fill with money at the same time.