You don't state if you have public or private addresses.
Specifically 'same level of protection' as typical home user is NAPT, i.e. inbound connections are not possible unless equivalent outbound exists.
If you have private addresses you've already configured NAPT if the connection works, and you have equivalent security.
If you have public addresses you'd need to configure stateful firewall to get same level of security
ip inspect name DEFAULT udp
ip inspect name DEFAULT tcp
ip inspect name DEFAULT icmp
int WAN
ip access-group DEFAULT in
ip inspect DEFAULT out
!
ip access-list extended DEFAULT
deny ip any any
!
Could work as a starting point. If you need to open up something inbound, add it to DEFAULT ACL, e.g. if you want to allow ssh in from world to given PC at home
ip access-list extended DEFAULT
permit tcp any host MY_SERVER eq 22
deny ip any any