This is a warning that is obvious when you think about it, but caught me out once!
If you're ever tempted to put a car up on ramps and then jack the other end and put it on axle stands then beware. If you put the front on the ramps then jack the back with a trolley jack the first side is ok but as soon as the second wheel comes of the ground you no longer have the hand brake working and at near full lift the trolley jack starts to pull the car backwards! !
Always back the car onto the ramps and use the axle stands on the front, or alternatively when the front is on the ramps lash the suspension to the stands so the car cannot move backwards.