Don't be afraid to use lines. For an hour, a guy at a ramp in Dubuque, Iowa, tried to angle his trailer every way imaginable to catch the bow of his friend's boat, which was being swept by a mighty wind and the mighty current of the Mississippi. Finally, I stood on an upwind pier and had the guy cleat a long line to his stern and bow; using the pier as a fulcrum, we got the boat broadside to the wind, then onto the trailer. No problem.
Don't assume there's only one way to do things. I heard a guy screaming at his son at a campside ramp in Wichita, Kansas. I was afraid the old man would have a stroke. "Put your hand on the bottom of the steering wheel, use your mirrors and steer the direction you want the trailer to go!" he yelled again and again. Now, I don't use this steering technique, and I have parallel parked a trailer in New York City rush hour traffic. Instead, I twist my upper body so I'm facing over my right shoulder. Looking out the back window at the centerline of the rig, I inch back, briefly rotating my head to glance at the mirrors to make certain I'm going in the right direction.
Don't go whole hog down an unfamiliar launch ramp. Cairo, Illinois, was where an underpowered little Honda slid halfway down a steep ramp, only coming to a stop as the outdrive pranged the bottom. Seeing that the ramp was covered in slime, the driver should have backed down only halfway and then pulled forward, testing the ramp to make sure he could climb up it unaided. For all I know, he may still be there trying to haul out.
Don't forget the engine. Lake Powell, Arizona, was the scene of a perfect one-try load of an outboard fishboat. The woman onboard raised the drive and then hurried to the bow to secure her boat to the trailer. She quickly climbed in her Dodge pickup's air-conditioned cab and pulled the boat to the top of the mile-long ramp. Of course, while she was driving up the ramp, a strange sound was coming from her boat's engine, which was still running...but not for long. At least she remembered to raise the motor.
Don't take anyone's word for it. I imagine what was said in the Ford pickup in Annapolis, Maryland, was "Unhook the boat." What I saw was the passenger get out, go to the back of a truck, unhook the trailer from the hitch ball, and give the thumbs up to the driver. What ensued was a nightmare of crushed metal, wood (the dock), and fiberglass. The driver of the Ford was also the unfortunate owner of the boat. His mistake? He didn't get out and check that his orders were being followed properly. What I took from the scene was a picture from my trip that I won't soon forget.