My procedure.....
Open Low Point Drains, open faucets, drain water heater, drain fresh water tank.
Once drained I close the Low Point Drains, close faucets, turn Water Heater Bypass Valve on.
Leave Anode Rod / Drain out along with fresh water tank plug. Put both inside of water heater behind access door. Then they are right there come Spring Time.
Remove inbound water connection from water pump and attach antifreeze suction hose. Submerge line in antifreeze and kick the pump on. You will see about a third of the jug disappear before pump kicks out provided you have closed all faucets and bypassed the water heater. Start with the fixture closest to the pump, crack the cold until you see pink, then the hot until you see pink.
Work your way up or down depending on your layout. Don't forget the outside shower..
Watch the jug and change it before it goes dry and sucks air. Once all fixtures are done drain suction hose (I pick the end of the hose up and crack a nearby faucet and the pump will suck the hose dry, no mess), close faucet, shut pump off and then re-attach the coach water line back on the pump.
Combine remainder and hit the sink traps and toilet slide.
I can do the entire trailer including toilet and sink traps with two gallons of R/V Antifreeze. Once I figured it all out I quit blowing it with air.