Ah, certainly. I was getting the picture of 10 people total with a cat6 between two adjacent buildings. Ok, so what I recommend is using 192.168.10/24 at the first site and 192.168.20/24 for the second site. The reason you probably shouldn't use 192.168.0 or 192.168.1 is that most consumer ethernet enabled devices have these IPs as default, so it allows accidental disruption from rogue devices connected by users. Here's what I think would be good in your situation:
(3 routers) Main router at Site 1 has a public IP WAN side and 192.168.100.254 LAN side. Site 1 router has 192.168.100.10 WAN side and 192.168.10.254 LAN side. Site 2 router has 192.168.100.20 WAN side and 192.168.20.254 LAN side. Site 1 is on subnet 192.168.10/24 and Site 2 is on Subnet 192.168.20/24
