Three best practices when configuring self-registration for an Experience Cloud site are A, B, and C. Self-registration is a feature that allows users to create their own accounts on your Experience Cloud site without an invitation. To configure self-registration, you need to assign a default profile for self-registered users, which determines their access level and permissions on your site. A best practice is to assign a cloned standard site profile as the default, which gives you more control over the settings and customization of the profile. Another best practice is to use a restrictive default profile to begin with, which limits the access and visibility of self-registered users until they are verified or approved by an administrator. A third best practice is to create a separate profile for your self-service site and your partner portal, which allows you to differentiate the access and functionality of different types of users on your sites.