Drain it and have it blown out (few supply systems actually drain completely without help form some air pressure).

The waste lines need antifreeze in every trap.
Toilet bowls freeze and crack just as easily as anything else.

turn off the breaker to the HWH then drain it.

As to the outside bibs, it depends on when it was build. They may have separate cutoffs for each bib inside the house that you would turn off, then open the bib. But if they are those newer style faucets where the valve is actually inside the heated space, then you just turn them off (there is a vacuum break on top of the valve).

ditto what B says about the drains, especially for WCs on an outside wall space. And turn off the main supply. Also ditto on the drains for the washer and dishwasher if it can get that cold where they are.

Turn the house "main water supply valve" off and drain the house water distrubution system by opening a faucet at the lowest point in the house, (usually an outside hose bib or a faucet in the basement.) While the faucet is open to drain the system go through the house and open all fauctts to vent the lines and let the water flow out.

Even a full water heater will freeze and break. Make sure you turn off the gas or electric supply to the water heater, then drain the water heater.

Use air pressure to insure all the water is drained out of the supply lines.

If you have a house over a crawl space, quite often water lines are brought into the living space, then stubbed down below the floor and run across the house to another location where they are stubbed up again. This is especially common for the hot water lines where they drop down from the WH then run to the kitchen or bathrooms. Where those lines drop down then stub up again they form a trap and even with air pressure it is unlikely that you can completely drain them. I generally go under the house and cut the lines and install a union about mid run so they will definitely drain. If you have copper pipes and your a bit reluctant to solder you may install a compression type union. Just be sure to leave the union disconnected all winter. It is easy enough to reconnect it when your ready to move back in the house.

DO NOT USE AUTOMOTIVE TYPE ANTIFREEZE-it is deadly poisonous. Go to a Camper/motorhome supply and get two gallons of "Food Grade Antifreeze"

Mix the anitfreeze according to directions, usually a 50/50 mix with water then pour about a pint in each kitchen, lavatory, laundry or utility sink drain, shower drains & floor drains to protect the traps. After you fill the traps pour a 1/8 cup of cooking oil in the drain to prevent evaporation. (It is vitally important to keep the traps full to prevent sewer gas from entering the house).

Turn the water supply off to the water closet (toilet) and flush the W.C. to empty the tank. Now pour about a gallon of the antifreeze mix in the W.C. bowl. A better solution is to pull the w.c. and lay in on its side in the bathtub to allow all the water to drain out and plug the drain hole with a test plug.

If you have a combination tub/shower turn the tub/shower diverter to the tub function. That will allow any residual water in the shower head riser to drain out into the tub.

If you have a dedicated shower the shower mixer control should be pulled out and left out all winter. I generally place all the parts in a plastic bag and hang that from the shower head so I will know where they are when I am ready for startup again.

Now, pour some of the antifreeze in both the washing machine and the dishwasher and run the machines in the drain cycle for a few moments. That will insure you have antifreeze in an residual water in the bottom of the machines tub and any inaccessible portions of the drain. lines. Also be sure to pour some antifreeze and oil down the washer standpipe.