Generally, winters are not cold enough to require winterizing irrigation systems. If you have drip irrigation, you probably don't need to do anything. Real sprinklers on risers might need something. I suggest asking your neighbors what they do.
Whatever you do, you will still need to provide water to your plants over the winter - there just isn't enough precip in the winter to keep roots going, at least the way most of us plant.
We do not winterize and I irrigate for 20 minutes if we have not had significant precip for 3 weeks - your mileage may vary.
Maintenance on irrigation systems is actually pretty straightforward and will not require a professional if you are willing to do the work yourself.
A little off topic, but since you are new to the area, if you have a swamp cooler, it will need maintenance and you should do that soon. Call a professional or ask a neighbor for advice - its not hard.
And be sure to disconnect any hoses from your outdoor hose bibs!!
The main valve and line should be turned off during the coldest part of the winter, particularly if parts of it are above ground. Nothing needs to be done with the water lines or drippers.