ISP MAN as router with Multiple sites. Config recommendations welcome

[johnevansab]

I'm new to networking (I'm a server guy).

I have five sites:
Site 1: 10.2.12.X 255.255.255.0 (Procurve 54xx)
Gateway: 10.2.12.1 (ISP MAN)
IP: 10.2.12.2
Site 2: 10.2.21.X 255.255.255.0 (Procurve 2910)
Gateway: 10.2.21.1 (ISP MAN)
IP: 10.2.21.1
Site 3: 10.2.22.X 255.255.255.0 (Procurve 2910)
Gateway: 10.2.22.1 (ISP MAN)
IP: 10.22.22.2
Site 4: 10.2.23.X 255.255.255.0 (Procurve 2910)
Gateway: 10.2.23.1 (ISP MAN)
IP: 10.2.23.2
Site 5: 10.222.222.X 255.255.254.0 (Procurve 54xx)
Gateway: 10.222.222.254 (Router)
IP 10.222.222.253

INTERNET SETTINGS:
GATEWAY 207.228.83.49 255.255.255.240
Useable IPS: 207.228.83.50-63
VLAN 100 (Defined by ISP)

The ISP MAN will be doing all the routing.

VLAN 1: DEFAULT_VLAN
VLAN 2: VOIP (MITEL 3300)
VLAN 3: Point of Sale Terminus (Moneris) (This can't be accessible by the rest of the network)

Only SITE 1&2 are setup by the ISP: They are passing traffic to each other.

Anyone have a config that will ensure security?