Usually people advertise their Minecraft server on server lists for free such as those mentioned before:

TopG Minecraft Servers

https://minecraftservers.org/

https://minecraft-server-list.com/

https://minecraft-mp.com/

https://list-minecraft-server.com

https://minecraft-server.net/

But I found it valuable to go to newer free voting sites with much less competition, since it can be difficult to compete with all the big servers out there already. And plus, it will be easier for you to gain an early advantage on others when/if their site somehow blows up.

Here are some of the personal ones I use (with votifier enabled):

https://mcservertime.com/

https://crackedminecraftservers.com/

https://goodminecraftservers.net/