Like a lot of this stuff, the first time doing it, it seems kinda hard, but after your done, you feel like a pro..
I did my O2 sensor once and it is a fairly simple job. Lots of articles on the web about doing it the hi-tech way, which requires you measure output voltage and such, but if your engine is running OK, I see no reason to do that.
For regular preventative maintenance, cleaning the O2 sensor is probably a good idea once per season, or a a minimum, once ever other depending on hours.
Once I got the sensor out of the cast iron holder (part that attaches to the block), I soaked it first in Ring Free, then some Carb cleaner. Never soak more than the tip. Be sure to also clean the "dogbone" piece that transfers the gasses from the block to the sensor.