Hi Annette,
Supplying them with a copy of your T&Cs of business, privacy policy and a form to complete which asks for full name, address, liaison (if more than one person to deal with) and invoicing details, and some questions to help you complete the contract with tasks/jobs they want you to do is useful.
I do my calls on zoom so I can record them and then go back and rewatch and make notes if wanted. If the call is unsuccessful it’s useful to see if there is a reason I can see, if it’s successful it’s useful to see exactly what they said they wanted during the call.
If you have anything legal you need to do - anti-money laundering for example if you offer bookkeeping creating a pack of forms and documents that you can send out makes things easy for you and looks professional.