Good setup for a larger site

Hi. I wanted to get some information from more advanced users.

I have a site that serves about 400-500 people online.
I run it as a hobbyist, I can configure a server and this is where I would like to get your advice.
I will add that it stands on wordpress. I am buying a new hosting to make it more efficient.

What configuration would be the best option?
A mariaDB database?
Web server in what best configuration? Of course Apache is out of the question
I mean the main server as nginx and phpfm?
What mail client, ftp?
Thanks.