Working in and around heavy vehicles like trucks presents many challenges to your personal safety. Something as simple as entering or exiting a truck tractor cab can be dangerous if you don't do it properly. Even veteran drivers can sustain injuries if they become careless.
Approach the cab. Before you even start to get in it, eyeball the footholds or steps. Make sure they're not dirty or greasy. In winter, check that they're free of ice or snow. Stepping on slick surfaces could cause you to slip and fall.
Use the Three-Point Stance. Have at least three points of contact between you and the vehicle at all times.
Enter using both hands and one foot, or both feet and one hand. For example, enter the cab with one foot on the ground and one on the truck's foothold or lowest step. Establish the third point of contact with a firm grip on the handhold on the cab frame exterior.
As you raise one foot from the ground, grip the handhold inside the door with your free hand. Establish three points of contact with one foot on a step, one hand gripping the handhold inside the door and the other hand gripping the handhold on the cab frame exterior.
When you have one foot on the top step, place your other foot on that same step or on the truck's floorboard. Continue to grip at least one handhold to maintain three points of contact until you have placed both feet on the truck's floorboard. Once you are safely and securely inside the cab, you can release the handhold.
Exit the truck by climbing out backward, as if you were using a ladder. Again, have three points of contact at all times. Never jump out of the cab. Use the Three-Point Stance when you're taking your Commercial Driver's License Skills Test. Some states may count failing to enter and exit the cab safely as an error.