Tor Exit bad practice: you shouldn't use domains that you do not own
Explicitly mention that relay operators should not use the domain that you do not own in the whois/DNS as a name pointer, for example, point to exit.torproject.org.
Reverse DNS and WHOIS record
Before turning your non-exit relay into an exit relay, ensure that you have set a reverse DNS record (PTR) to make it more obvious that this is a tor exit relay. Something like "tor-exit" it its name is a good start.
If your provider offers it, make sure your WHOIS record contains clear indications that this is a Tor exit relay. https://community.torproject.org/relay/setup/exit/