good discussion as referenced above by dave. I have read that and am in the super minority when loading and unloading.
This is what I do, for what it's worth.
Unloading:
prepare area (if you have one). Turn on battery, turn on blower, check that both drain plugs are in (transom and t handle midship), unhook all straps.
Everybody in boat except driver of tow vehicle: back down ramp slowly and smoothly until trailer fenders are below water line a few inches, driver then stops quickly, boat will smoothly slide off trailer with little rubbing on bunks. Start the boat and continue in reverse. Turn boat around and idle way away from launch ramp to leave room for everyone else. Float, with engine at idle warming up while you listen to tunes, fill up ballast, put up bimini, etc. When boat driver reaches dock, go get them and picked up from your bow... then go shred.
Loading:
Drop off vehicle driver only and then drive far away from dock and wait. Use this time to finish emptying ballast, ice chests, putting bimini away, cleaning up. When you see your truck and trailer at top of ramp, idle towards it. Driver sinks trailer so trailer fenders are a few inches under water but leaves tranny in reverse. Idle boat slowly onto trailer until it stops. The trailer will center the boat on the bunks. Throttle boat forward with steering wheel straight until the front U-bolt hits the roller. If you are at half throttle and the boat will not slide anymore, then keep throttle in that position and have driver of truck SLOWLY and smoothly back up until your boat hits the roller. Truck stops, put the boat trans in neutral, if the boat does not slide back at all*, then turn off boat, truck then SLOWLY and SMOOTHLY drives up the ramp to the "wipe down" area. Connect all your straps (bow and transom-if you have those) Everyone on boat gets themselves and all their crap out, wipes down boat and goes home
I have a lot of bow lead so I have to keep a little forward throttle as the truck driver begins pulling out. As soon as the trailer tires get out of water I throw it in neutral and cut the engine before the sea-water pickup hole is out of the water, even though there is a lot of water keeping that sea water impeller wet.
As a new boat owner, I would not load your boat the way I do it, but I would definitely unload it the same way as I do. No need to pull your boat off the trailer in reverse with a cold, under lubricated motor that has been running for a few seconds... plus there is no need for that, just let it slide off.