How to find available IP addresses when DHCP isn't working (Guide for Macs)

I needed to set my laptop to a static ip because the router's DHCP service wasn't issuing me one regardless of how many times I renewed it. I found this Stack Exchange Article that featured a really handy terminal command:

ifconfig | grep broadcast && arp -a

This produces a list of all devices (and their IPs) that respond to the broadcast. My network was pretty small, and the IPs are in order so you can find a gap that doesn't seem to have a device and try it out.