I'll add to that. Don't take too big a bite when backing.
Some people try to do it all in one or two maneuvers. When simply stopping after backing 5-6 feet, then resetting the steer position (with a possible pull up of a couple of feet) would simplify the entire issue. Corrective moves should be done in small increments, in tight quarters.
It may not look "smooth". But if it gets the job done and reduces your stress levels.....who cares.
I may laugh at the rookie having a difficult time...in an obviously easy backing situation. BUT if he/she does it without causing damage...he/she is "good" in my book.
Take the time to teach yourself some tough backing situations. When you go to the truck stops and shipper/receivers try and back into some of the tougher spots instead of the easy ones. When it comes time to shine you will be used to it.