Before creating a trust between two Active Directory domains, it is important to consider the following:

1. Check that the DNS infrastructure between the two domains is properly set up and that the domains can successfully communicate with each other.
2. Check outbound and inbound firewall rules for both the domains.
3. Ensure both the domains are using compatible Kerberos versions.
4. Check that the version of Windows is the same or higher level in the trusting domain than the trusted domain.
5. Ensure that the trust direction fulfils the necessary requirements.
6. Verify that computer accounts already exist in the trusted domain.