Need advice for proper set up of 2 routers 1 modem

Hey everyone,

I am in the process of optimizing the network at the small business I work at and could use some advice.

Here's my setup:
Charter Cable Internet with static IP
Modem: Modem/Router Combo unit ( I forgot to grab the model number before I left work)
Router 1: Asus RT-N66U
Router 2: Belkin Unit ( I forgot to grab the model number before I left work)
Gigabit Switch
(If you need the specific models of the modem or router 2 I can get those later tonight when I'm back at work)
Right now I have Router 1 connected to the Modem pointed at the static IP and Router 2 connected into Router 1. Router 1 is handling the DHCP Server.

My ideal setup, unlike my current setup, would have the 2 routers on seperate internal networks since they are for 2 different business within the building.

Would connecting both routers to the modem and directing them to the static IP work? Or would that just cause conflicts?

What would be the suggested configuration of this system?

Thanks