Security settings to prevent fake/ hijacked payment links/ forms

Good day,

We just started with Cloudflare in our eShop. Main purpose is to prevent/ avoid potential problems related to security.
Documentation is big and not everything is clear, this is our probem, we do not know what to look for.

Our first target is to prevent hijacked forms/ links which leads customers to fake areas, where they can leave personal data (bank account and credit card info.).

We are looking how to setup our Security ruls properly. Here is not sure what has to be done, or is working out of the box.

Any help even small hint will be very valuable. Many tyanks !!!