always reverse on / drive off on a green light !!..never take chances even when you are given your keys and told you are tipped !! 
if someone is on the bay next to you use them as a guide as when your cab is nearly in line with theirs then you know you are about to hit the bay…unless they are driving a rigid then have just reversed your truck halfway into the warehouse !! 
oh and if its a drop and swap…dont forget to take your number plate off the trailer first !! 