The easiest way is to configure the settings (control panel) to put the monitor on standby more often. Secondly, lower the brightness down to tolerable levels. It'll take some time to get used to, but one gets used to it after a while
But in terms of power consumption, assuming you have an LCD one, it doesn't suck up much power compared to the rest of your system. I feel reducing the power of the CPU, etc, is more important because those components are the ones that will be continuously running. Monitors can be switched off if you're running an background process such as a virus scan and so on.