It really depends on your requirements...
But a few useful points:
- Use GPT partition table and not MBR. Everything will be simpler, no need for extended/logical partitions.
- If you need to be able to do online (mounted) partition resizing, pick btrfs. Ext4 can only grow them online but not shrink.
- Make sure your partition boundaries are 1 MiB aligned.
- If you need more advanced setups, consider using LVM.
Of course it depends on what software you are using.
Though as a rule of thumb, peers try to connect directly. That's not always possible due to firewalls/NATs, so often TURN servers are used as intermediary.