Anyone into vps security?

Currently running a little proxy website which uses socks5.

This proxy is ONLY to be used for skype atm and i want to eliminate as much security holes as I can.

-So far all i was able to do was change default ssh port.
-Block port 80 and some default torrent tracker ports. Would be nice to block the entire ability to use bittorent but not sure how that’d affect skype.
-edited /etc/security/limits.conf to hard maxlogins 0 so they wont have ssh access.

Any other tips/recommendations.

It’s still a real small thing we have going, so my money is limited and I know this security industry isn’t cheap, but i’d really appreciate any help/advice as possible.

I also dont mind throwing some temporary logins your way if you guys would like to test it out and see any loopholes etc.