My method...in Pennsylvania where it can get very cold.
My lines are almost empty because I opened all of the valves and let all of the lines drain out of the low lever drain pipe during my last trip. Natural movement of the unit seems to eliminate all of the water from even the lowest lines.
I close the water tank valve, pump RV antifreeze through all of the spigots (kitchen, bath vanity & shower), toilet valve and outside shower. Don't forget to keep some in the toilet bowl.
Adding antifreeze to the black & gray tanks is advised if you think that you may have some residual fluid there.
Also, be sure to release pressure on the external water supply valve until pink comes out of that.
I then pour about 1 pint of antifreeze into each trap...don't forget the shower.
Once everything has been winterized, I open all spigots and place a small bucket under the low level drain valve.
I open this valve and drain out all of the antifreeze that can drain, by gravity.
I collect about 1 1/2 gal and keep this for future use in traps, etc.
Removing this antifreeze makes the first fill up easier and quicker. Less water in the gray tank.
Last, I remove the water tank drain plug and use a small plastic hose to remove remaining water from the tank via siphon. I was surprised to get about a quart out. What little is left in the tank will not create a problem if it freezes. Plug is installed for the next tank fill up.