Summarize this article:

If your oximeter is battery-powered, be sure to keep it charged. That way if you need it in a hurry, it will be ready for use right away. Inevitably your oximeter will get dirty from use. Keeping the probe clean is important for two reasons. First, dirt and dust can block light emitted by the oximeter and lead to inaccurate readings. Second, buildup of microorganisms on the probe can cause an infection when you put it on.  Use a lightly damp cloth or paper towel to wipe away dirt. Use an alcohol swab to kill bacteria and viruses. Make sure your oximeter is somewhere it won't get knocked over and damaged. If your oximeter is the plug-in type, make sure all plugs are out of the way and won't be tripped over. When unplugging a cable, you should always grab the plug itself, never the wire. This could damage the internal wiring and lead to a fire hazard.

Summary:
Keep the battery charged at all times. Clean the probe section of the oximeter. Store your oximeter in a safe place. Disconnect all wires properly.