Get attuned to the particular tension of your truck's clutch. Not an issue for an automatic, but old manual trucks tend to have harder gear change ratios than smaller vehicles. Get used to putting the truck into first to keep from getting stranded at some busy intersection, or stalling out in traffic.
Use your mirrors. You won't be able to just look through your windows, so you'll have to check for surrounding traffic or pedestrians by checking the mirrors on your driver's side and passenger's side. Despite blind spots, checking the mirrors will let you know when you are clear to move.
Don't make quick moves. This applies largely to changing lanes. You won't always be able to tell with your mirrors whether there is a car right behind you or catty-corner from your back. One way to make certain that you are clear is to change lanes slowly. Signal before you start to shift lanes. Then slowly shift into the lane. Wait a second and listen for horns. Ease over to make sure you're not entering someone else's lane.
Use caution when backing up. Taking your time makes the move safer, and using your mirrors while angling can be an effective way to see if any pedestrians are in your path.
When turning, pull straight forward before cutting the wheel hard to execute the turn. Turning a box truck like you would a car can take you straight over the curb for a jarring ride. You have to make sure the vehicle clears the corner before turning.
