Lot of good info here, and to make a point; you would want to stay away from the far side curb and be more towards the middle, or closer to your curb. The reason is the front of the truck will swing OUT as you back in and you're more likely to hit something with the front of your truck while backing in that you are with the back of your trailer.
Newbies are concentrating on the back of the trailer and understandably not wanting to hit something backing up, while they swing the front of their truck into a pole or another vehicle. WATCH THE FRONT OF YOUR TRUCK TOO WHILE BACKING UP.
For this reason, you would not want to start on the far curb as you would very likely be into the curb with your front truck wheels.
All it takes is practice; I've been doing it for 14 years on several hundred trips and I'm still practicing!!