Your printer setup menu should have an option to pick a fixed IP address. Your router will have a menu showing what range of IP addresses it is able to hand out. Simply pick a number outside that range for the printer. So if the router is handing out numbers in the range, say, 192.168.0.2 to 192.168.0.64, choose something between 65 and 254. If the router is set to hand out all possible addresses, you can change one of the limits to give yourself a bit of space.
Some consumer-grade routers can be set up somewhat differently, but you get the idea.
Fixed IP addresses aren't a security risk.