File Access over https safe I have a mac mini server at home that has a USB 3.0 storage device attached where I store all my files. Anything from iTunes, iPhoto, documents, etc. 

I want to know how safe it is by creating a VPN connection from my MacBook from anywhere in the world and accessing https://webdav.myserver.com and writing/reading files?

Is there anything I can do to make reading/writing more secure?

https://webdav.myserver.com will not be accessible over the web unless there's a VPN connection.
You could try to access your files using SSH (we call it SFTP). 

To enable this feature on your server, navigate to System Preferences -> Remote Login and check it. You can also select which account has access to your server.

To access your file using SSH, you can either use command line (ssh) or GUI, for example Transmit (paid), CyberDuck (free)