I have seen a LOT of different ways people tie their rigs to the trailers and have heard a LOT of different reasons why (some are better than others ). Lets put up some pics and pointers on securing ATVs for trailering.
I have found that tying ratchet straps to the undercarriage or axles seem to be the most secure for me. I have had a few straps come loose when I strapped them to the racks due to the suspension flexing on the machine bouncing over frost heaves and bumps. If you tie directly to the frame or axle of the machine, there is no bounce.
Any other pointers?