1- enable DHCP snooping:
ip dhcp snooping
2-appply it for example vlans you need secured
ip dhcp snooping vlan 10
3-excelude it on port where you receive DHCP offers from
ip dhcp snooping trust
4-Create a location to TFTP database to in case your box reloadsso you can fetch previous bindings.
ip dhcp snooping database tftp://172.16.1.1/DHCP/RTR1.dhcp
HTH
Sam