If you are new to foaming milk, start out with plenty of milk – at least a third of a one litre foaming jug. The reason for this is simple – a small amount gets very hot startlingly quickly, so a larger quantity is easier to work with.
To texture milk, keep the nozzle on the steam injector close to the top of the milk and open the steam valve fully – your aim is to tuck the air in, in very small bursts and in quick succession. When the air is tucked in, keep the nozzle just below the surface of the milk, while maintaining a tight spin.
Disperse any big bubbles by tapping the base of the jug on the work surface. Fold out with a shaking action (this makes sure that the foam and milk are mixed evenly together). Use as quickly as possible after foaming – left in the jug, it stiffens up.
For a latte, use the same process, with less air at the beginning.