Calling in Zoom is the best way to start working together.
Carefully read the contract, everything that is not spelled out in the contract will be paid additionally and is not included in the price. The contract also specifies the expiration date of the contract, and if the deadlines are violated, the resumption of work is possible only after the renegotiation of a new contract, while the cost of work may change in a big way. Together with the contract, you will need to fill out a short brief, it allows you to summarize our discussion, as well as make links to references (sites that you like) as a guide in the work.
I always record a video presentation of the project, with detailed explanations.