Step1: Configure the Interfaces with IP Addresses.
i) LAN Interface with Private IP Address
ii) WAN Interface with Public IP Address
iii) Management Interface with Private/ Public IP Address
Step2: Once you setup Network Interfaces, Next thing you need to configure is Routing in the Firewall.
i) Default Route Pointing Towards the Internet
ii) Static Route Pointing Towards the Servers or Other Networks.
Step 3: Now we need to configure Routing Policies ( Access- Lists) in the Firewall.
i) Which Traffic Should be Allowed in the network.
ii) Which Applications are allowed to run in the network.
Step4: Configure NAT ( Network Address Translation ) so that users in the network can access outside the network ( Internet).
i) Static NAT for Servers
ii) Dynamic NAT or PAT for End Users.
Step 5: Change the Basic Settings of the Firewall.
i) Admin Password
ii) Hostname
iii) DNS Server IP Address
iv) HTTP/HTTPS Access
Reference: Cisco