Normally I just set the DHCP server to hand out addresses in a portion of the subnet, then I just assign statics in the remaining space.

ie. your home network runs in the 192.168.0.0/24 address space. Set the DHCP server to hand out addresses from 192.168.0.50 to 192.168.0.254. Then assign addresses from the 192.168.0.1 to 192.168.0.49 range to your static devices. Bear in mind one of those addresses is likely to be your router address so you can't use that one. Mine are always at .1.

I've seen users on other forums telling people to just use the DHCP address they were given and set it as a static. It'll probably work until the DHCP server assigns that address to someone else. You don't want to do that.