Configure a secure Centos 7 Server on VPS

I need to configure a Centos 7 VPS to host some game servers and a website, i'd like to know what should i do to secure it to face possible threats.

Here's what i've installed on the vps and what i did until now:

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  LEMP STACK NGIX, PHP, MariaDB: secured mysql installation, disabled remote root login, removed test database. Do i need to enable any kind of log for security purposes? It's enaugh? What about FTP? Which one is a good ftp deamon?

  
  


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  SSH: I disabled root login and changed the default port with a custom one. I use SSH to log with three different users. Do i need to enable any kind of ssh log? Do i need to use private keys?

  
  
  
  
  • Installed firewalld: I didn't configure it yet because i don't know how to do that in a good way. Can you explain or give me a link to configure it?
  
  
  
  

Do i need to do more actions to secure my server? Actually just to start, i need to host a minecraft server and a website on it. Can you give me some advices?

Thanks and sorry for my english.