Here's a very brief list of things that you can do around the house before it gets too cold.
1. Clean the windows - The winter sun can be wonderful. Clean the windows so you don't miss any of it. The weather outside will be more moderate and make it a lot easier for you to take your time without sweltering or freezing.
2. Get the heating and air checked - Now it the perfect time to get the furnace, air conditioning, or heat pump checked out. Filters can be changed and the system can be checked for leaks. It will only take about an hour for an expert to do it, but it can save you thousands down the road.
3. New appliances - The new models are being released and the older models are being sold off. Watch for great deals over the holidays or stop off in the showroom to see what the dealers are selling at a great price. "Last year's" model is probably going to be perfect for what you need. Plus it's a lot better than waiting for the dishwasher or dryer to simply give out.
4. Time for a chimney sweep - If you have a fireplace, have a chimney sweep come and inspect the chimney and clean it. Even here in Las Vegas, the nights can get a little cold. You want to be able to light a fire without worrying that you're going to burn down the house. They can also do an inspection to ensure that the chimney is in good shape and that nothing needs to be done. You can ask that they check that your fireplace insert or wood stove is connected properly, as well.
5. Insulate pipes - Not a huge deal in the Las Vegas area, but go even a little way into the mountains and you might find yourself in a cold zone. It only takes one really cold night to freeze the pipes. Insulating your pipes is easy. Pick up pipe insulation at the hardware store and wrap it around the pipes. It will save on hot water heating, as well. In many homes, especially older ones, the hot water pipes are exposed to the outside air. The underside of the house won't ever get to the 120 °F that your hot water heater does.
These are a few of the things that you can do to winterize your home and get it ready for colder nights and the rainy season in the Las Vegas valley.