If you get out of your cab and have a look at the front and rear you will see that your cab has bumpers,

but try turning the round thing in front of you first, its called a steering wheel turning it all the way in one direction helps, then in the middle of the cab there is a stick with numbers on it put it in number 1 put right foot down on right hand peddle and lift your left foot slowly then you should be able to get out in one,
seriously though always leave room to get out in one go, if you look along the bonnet as you aproach the cab in front, whatch for when the rear wheels of the cab in front start to disappear, stop and you will find that you can now get out no problem