Configuration between a cisco 2600 router and a cable modem

I have a cisco 2621 router and a 2950 swtich in which i want to set up in my home network. i understand the configurations for my local network but its the configuration between my Cisco router and the cable modem that have me puzzled. I know i will have to use NAT when it comes to traffic on the interface that is connected to the modem but its the access list that giving me some trouble. Can anyone suggest ACLs that will have make my network secure from outsiders.