You may want your client to pay a part/full fee at the time an appointment is booked. This could be because you want to charge them in advance, or because you want to charge a small deposit to keep in case of appointment cancellation.
If you want to request a client payment whilst booking an appointment, there are a few ways in which this can be done.
Firstly, you should create a payment service for payment. You can click here to learn how to create payment services. In the case this is a part-fee, then the payment service should be for a smaller amount than the full price.
Then, every time you have a new client, you have several options:
You can generate a link to your payment page (click here for details) and then edit your appointment booking email template to say that on top of booking an appointment, your client should also pay in advance. You can click here to learn how to edit appointment slots email templates
You can generate a link to your payment page as mentioned in option 2, and then include this link in your appointment confirmation email (e.g. the email a client gets after you confirm their appointment, rather than when booking). You can click here to learn how to confirm appointment suggestions from clients, and you can click here to learn how to edit calendar email templates
You can add links or a web widget in your website and instruct clients to both book an appointment and also pay online prior to an appointment. You can click here to learn more about web integration