Absolutely practice! And yes, don't oversteer. I think that is the tendency. You're having to think in reverse of how one would normally steer so your synapses don't fire fast enough and then you end up oversteering to try and compensate.
If you think backin' your rig up is hard, try backing an airplane out of a hangar! I was scared sh!tless the first time I had to do that. There were other planes and huge hangar doors in very close proximity. You have 3 pivot points, the front wheels of the tractor, the towbar hookup and the nosewheel on the aircraft compounding the problem. By the time my brain figured out which way to turn the steering wheel, it was already too late, the nosewheel had turned too much and the plane was cockeyed. After that, any time we had a plane to move, I'd do it for practice. After a bit, I probably coulda done it with my eyes closed.
Find yourself a parking lot, eh. And get to where you don't have to think so hard about it, you just do it as if you'd just run to the store for a six pack and now you're pulling back in your driveway.
David