When I load a car on a trailer, front gets a chain put on as tight as possible, then I push the car back, then use a chain binder to tighten everything up. Chain binders are what you see on logging trucks and equivalent. So if using that basic tecnique, use a chain or very thick rope on the front, then use the rachet on the back to tighten it down nice and snug. If unsure of your rope or strap quality, use two of each. Better to be safe than sorry.
If you have a winch like minnowguy. Just make sure you do not over tighten things and end up bending/breaking whatever you anchor the rear of the atv to.
Matt