When a user decides to proceed to the payment of his order, it is crucial to make the experience as fluid as possible.
It is best to avoid unnecessary questions and forms, it must be done at the simplest.
You will find 2 important tips below:
Do NOT enable mandatory account creation: account creation is a drag on many buyers. Select "accounts are optional".
Remember to check "Use the shipping address as the default billing address" and "Enable automatic address entry".