........
When I asked one man what was holding the car onto his trailer, he looked at me as if I was mad and said the hand brake!
This was in a motorway service station, so perhaps I worry too much.
I used to help my mate out with local'ish recoveries using his Brian James car trailer. If I had a few miles to travel I would strap all four wheels to the trailer cleats to make sure it couldn't move from side to side or forwards and backwards but, if I only had to travel a couple of miles I thought I'd get away with leaving the winch cable hooked up. You soon learn how much a car will dance about from side rail to side rail when not properly secured.
I've never just relied on the winch, but often used two straps for short trips until I actually thought about it. When you've seen the vehicle bounce around the bed and have to unload it somehow, two straps is not a shortcut.
And if you do lose a load, you don't have a leg to stand on when you admit to only strapping two wheels rather than all four. Your boss is unlikely to stand behind you either.
So, there are some simple easy rules:
Handbrake on and front wheels straight, just like normal parking. But put it in gear as well.
Strap all four wheels with correctly rated and maintained straps.
The straps should not cross each other, but you do want them to be as long as possible.
Don't use the same cleat for the centre of both straps! This is depressingly common, and is stupid for obvious reasons
Once it's strapped down, slacken the winch cable.
When you've gone a couple of miles, stop and check that everything is how you left it. Do it right, and you'll rarely have to do anything extra.
The only exception to four straps is you're in a dangerous location, when the rule is get it loaded and get out of there as quickly as is safely possible. We were taught that if the location is really dangerous not to stop, but carry further on and arrange extra equipment and personnel. Once you've arrived on site, you're in charge of, and responsible for, the customer.
Securing a motorbike is interesting, but you have to be careful not to damage it. A strap over the top to pull it against the side stand is a BAD idea.