From cold and before switching on the ignition give the engine a few turns on the handle to overcome the oil resistance and get things moving.
Pull out choke and switch on ignition.
Engage the handle again and slowly turn until you're past the bottom of the turn and just before the next compression, you'll feel this easily enough.
DO NOT grip the handle as you normally would with your thumb underneath forming a ring. Try and place your thumb above the grip touching your index finger knuckle (does that make sense?).
Give the handle a sharp pull upwards, if engine doesn't start repeat until it does. It may take a few attempts before sufficient fuel is drawn into the cylinders.
When running don't forget to remove the handle completely and immediately, chances are you will forget it once you have entered the car to push choke in a bit etc.
The risk to your thumb if gripping the handle fully is "kick back" the engine fires but there is insufficient momentum to continue clockwise rotation, it turns rapidly anticlockwise and the handle hits your thumb. I've done it and it's sore!

Obviously the engine should start easier when warm/hot.