It's easy to stall the engine. Release the clutch quickly without any gas.
Why would you do that though? Probably because you want to move away quickly, for example, at a traffic light which has just turned green.
Try to release the clutch only as far as needed to make the vehicle start to move, and add gas. If the vehicle is starting to move at the speed you want, keep the clutch steady for a moment or two.
The point at which the engine starts to take the strain is known as the biting point, and you can feel it. When you feel the biting point try to keep the clutch still for a moment or two. It does take practice because the foot movements required can be surprisingly subtle. Keeping your left heel on the floor mat can often help to stabilise your foot on the clutch pedal.
